Tag Archives: quartz

4 Comments

To see the Blogging Hawks original post...

Wonders Lead to Discovery

Hello Blogging Hawks,

I know the previous class has tipped you off I am likely to visit your blog and, despite being very busy making DVDs/CDs and helping my local schools, I just had to drop in a comment about your latest post. I wonder if you all suspected I would interested in this post? I know previous classes learned of my interest in many things and geology as one in particular.

What a brilliant activity! I will have to try your experiment myself and see what results I can find.

The questions you started with are fascinating in themselves.

How are they formed? I know you discovered chemicals can invade spaces and, if the conditions are right, allow crystals to grow. what a natural wonder!

How long does it take? I think you also realised how long depends on the conditions. They can take millions of years or you can make them in a day. Did you notice no two of your geodes were exactly the same?

Where do you find them? Over the years, I have come across crystals protruding from the ground and clusters on rocks. It seems a game of chance if you're in a spot known for crystals or geodes. When we do a search on the internet, we realise geodes can be found in many places around the world. Here is a Wikipedia link on geodes...

Geodes

Can you really dye them? When I was your age, I wondered the same question. Like in your picture, I had seen beautiful colours in geode slices but soon learned they weren't always natural.

Crystals can, of course, be naturally coloured. We know diamonds can be clear, blue, yellow, brown, green, purple orange or even pink depending on small defects or impurities*. Quartz can also be clear, purple (amethyst), yellow (citrine) and other colours. I don't have any dyed geodes in my collection as I prefer natural colouring.

*Here's a little information I found. Blue diamonds are blue because they have boron impurities. Boron is part of borax.

Below you can see photos of some crystals in my collection.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Quartz from Northern Territory, Australia

 

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

Smoky Quartz

 

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

Citrine Quartz from Brazil

 

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

Iron Pyrite (Fool's Gold) from Australia's Northern Territory

Mr. B is certainly fabulous to bring in such an interesting experiment. I also liked the option to create a crystal snowflake. They may not look like a geode but each is special as, just like snowflakes and us, no two are exactly alike. That's what has interested me about geodes, each is unique even if they look almost exactly the same.

Look at the pictures below. Each is of a Brazilian geode in my collection. One has been cut in half while the other is complete. I decided long ago never to cut open the complete geode so what's inside remains a mystery. It could be incredibly beautiful but I treasure the intact geode. I wonder if any of you could resist cutting it open?

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Looking at your reflections...

Adam - You have shown what science experiments are often about. We take steps and wait to see
the results.

Shaye - I like your simile, "looks like a tiny city the way it sparkles". Good use of descriptive writing makes writing stories or explaining science easier to understand for readers and interesting.

Faith - You packed quite a bit of information into your comment. Adding "in my opinion" is a very good phrase. It tells readers the idea is yours and suggests others might have other ideas. You also introduced an idea, i.e. removing the yolks and albumin (white) from eggs to make them hollow. Did you know there are collections of bird eggs often found in museums, universities and even private collections? Collectors normally make small holes at either ends of an egg and blow out the contents. Can you imagine doing this for an ostrich egg?

Haya - Aquamarine may not be my birthstone but I do like the idea of making blue crystals. I like your suggestion it might be possible to make your name in crystals. I know it will work because you only need something for the crystals to grow on. Raindrops and snowflakes are the same, they need something to form on. In the sky, it might simply be dust.
On checking, it seems my birthstone is either topaz or citrine. I have citrine quartz in my collection. Here is a close-up photo of citrine quartz crystals

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Marcus - You have shown your knowledge of stones. Obsidian, volcanic glass, can be very dark and forms when lava, high in silica, cools quickly so minimal crystals form. I have seen natural obsidian in the crater of a volcano in New Zealand and have some in my collection (bought, not taken from the volcano as it isn't permitted). Below is a photo I took about 40 years ago on the edge of a crater in Mt. Tarawera, New Zealand.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Like you, I also like the reflection of light on crystal surfaces. What else is borax used for? Here is a Wikipedia link.

Borax

Liam - How interesting. You used green dye but your crystals seemed blackish. How could this be? Sometimes dyes can concentrate (get stronger) as the mix dries out or perhaps the crystals on your star were growing on something dark. I love mysteries. They encourage us to suppose what might have happened. Some of our great discoveries have come about when experiments didn't turn out as expected.

Riley - You have given a very good explanation of the process you used to make crystals. I also liked your suggestion the crystals looked life-like. Crystals grow as do we so it seems a little like life. Imagine if we were able to use time-lapse photography (pictures taken at regular times apart) to photograph the growth of your crystals then showed the photos one after the other as in a movie. We would see the crystals forming and growing.

Alvin - I liked your "wonder". The chemical reaction works quicker when in hot water. You can see this with sugar dissolving in water. If two of you each placed a spoon of sugar in containers of water where one had hot water and the other cold, I suspect you would find the sugar is dissolved more quickly in the hot water. What do you think?

Anita - I liked your use of "Step 1" and "Step 2" in your comment. Science, particularly chemistry, uses steps to carry out experiments. It looks like a cooking recipe. Follow the steps and you should bake a cake. Follow your class experiment and you should get crystals.
Why use borax? Borax dissolves easily in water and has water in its formula. Let's look at the chemistry involved...
Borax is sodium tetraborate decahydrate but I think it's easy to remember borax. The longer name tells us the chemical contains the elements sodium, four parts boron, and oxygen as well as 10 parts water. It's written like this...

borax

Na is sodium, B is boron and tetra tells us 4 parts, O is oxygen and there is also 10 parts water. It is a type of salt and can be found in crystal form. Below is a public domain photo of borax crystal I found through Wikimedia Commons. You can see borax can form crystals.

This work has been released into the public domain by its author, Aramgutang at the English Wikipedia project.

This work has been released into the public domain by its author, Aramgutang at the English Wikipedia project.

Carter - I like your explanation of the steps needed in order to carry out your class geode experiment. One of the keys to scientific research is recording information. Experimenters have to not only record what happens in an experiment, they have to record how an experiment was done. This is so other scientists can repeat an experiment to check the results.

Marah - I like your description of the appearance of your crystals. My imagination was sparked by the thought of a million cazillion crystals sparkling in the light. I know I enjoy the sparkle as light bounces off the facets (faces) of the crystals. I also liked your thought on what might happen if the borax wasn't completely dissolved. Science is full of "what if" questions and experiments to discover the answers.

Colby - How did the borax mix in with the dye? How and why do crystals grow on a pipe cleaner? What a great questions. It's good to be able to follow experiments but to wonder why things happen is real scientific thinking. Questioning why then finding answers is the sign of a mind full of curiosity.

William - I like your "wonder" thinking when you wondered if the crystals would continue to grow if you returned your geode to the mixture. I suspect, providing the chemicals aren't all used, the crystals would continue growing. Imagine filling and egg and making a solid crystal geode. Your idea made me wonder what might happen if, after the crystals have grown in the first borax/dye mix, the eggs were placed in a different dye colour/borax mix? Would you get two coloured crystals? Would the new mix dissolve the old crystals? Would the first crystals change colour? These questions could be a completely new experiment.

Sofie - Because of the photo, I can see your crystal star so I agree it is really cool. I also read your birthstone is sapphire. The area of Australia I live in is known as the Sapphire Coast. It's known for the colours of the sea and sky in summer. Below is a photo taken from a trail in my town.

  Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Did you know there is something known as the Moh Scale? It's used to describe how hard minerals are. At the very top at level 10 hardness is the diamond. Sapphire comes in at 9 so it is amongst the hardest.

MOH SCALE

Robert - It can happen in experiments. What was expected to happen doesn't exactly work out as planned but this has led to some good results. Perhaps you have used post-it sticky notes? They work so well because they can be stuck on, removed and replaced. Did you know the glue used was an unexpected result of an experiment? A scientist was trying to develop a very strong glue. The results of one experiment was the glue now used on post-it notes. He realised it was sticky enough to hold but could be removed and reused. I find science fascinating, especially when it finds something unexpectedly good.

Olivia - A couple people have written about their fake geodes. I find the "fake" idea interesting. If we were to accidentally spill chemicals on the ground and they seeped through the soil, found a space, and started to grow as crystals, would they be fake or real? People didn't try to make them but they could happen. Real geodes are ones made in nature but your geodes were made in class. Real or fake, aren't they amazing?

Thomas - I wonder if geodes can change? I liked your question. You now know natural geodes take much longer to form than the ones you made in class. Forming crystals can take a great deal of time and need the right conditions. Think of this unusual crystal idea. Diamonds can only be formed when deep underground under pressure and heat for a very long time. They are made of carbon. Can they change? Did you know they tend to only come near the surface when brought up by volcanic eruption? Being made of carbon, do you think some would burn up in the magma? Imagine burning diamonds.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

This is not a diamond. It's a glass replica. I can't afford to add a real diamond to my collection. 🙂

Thomas's thought may have been correct. If someone accidentally bumped the borax/dye mix when crystals started forming, the crystals might not form correctly. Also, using too little borax might mean crystals don't form correctly because there isn't enough of the chemicals. I like mysteries in science. It can be fun trying to find the answers.

Mani - Now there's an interesting idea, would the process work with laundry powder?
I looked up information about borates in laundry powder and found they have a number of effects to help in the cleaning process but no information about using borate detergent to make crystals. I think it might depend on how much borax was in the detergent. There might not be enough to have good crystal growth or possibly even the detergent might stop growth. That would need another experiment to find answers.

Saadia - It can be cool to experiment but I think the coolest part would be seeing how all of the geodes and stars looked at the end. Imagine having many crystal stars hanging in the sunlight. Light would be reflecting off them in so many directions.

Luisa - I also think your parents would be proud of what you have made. I know I would want to try the experiment again but remember to always have adult help when working with chemicals. When I have some time, I'm going to have to try to make geodes and stars just like your class. I wonder how they might look?

Prayers - I'm glad your class mentioned making either geodes or stars. I might have though of geodes but not stars. I wonder what other shapes I could make? Would I be able to join the shapes to make crystal patterns?
I also liked your question as to whether you could make crystals without the borax. You can also try using salt or sugar. Dissolve salt or sugar in warm water and allow the water to evaporate off in the sun. Small crystals would form but I think you would find your borax crystals are larger.

Aleah - Your curiosity asked you questions I also found interesting. Would the eggshell inside be white or would the dye have changed the shell to colour? I suspect there might have been some change of colour but that's a guess. I would also guess they feel like real crystals because they are real crystals you just happened to grow.

Bryan - I wonder how the borax turns to crystals? What a great "wonder". Chemistry, the way chemicals can work together, is very interesting. The borax dissolves easily in water and then crystalises out again. How?

HOW CRYSTALS FORM

Without dye, the borax would form white crystals. Look at the picture posted for Anita and you will see what natural borax crystals look like.

Oliver - I like your description of the snowflakes being uncanny. Uncanny means 'unnaturally strange 'but we know crystals form naturally. I also find them uncanny because their sometimes beauty seems unnatural.  Examining crystals and other stones under a magnifying glass or microscope can unlock some amazing images. I don't have a microscope but I did take some close up photos of some of my small crystals in one of my geodes. The first photo shows the geode and the other three are close up photos.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

There are so many wonders in our world and so many I have yet to discover. All we need do is keep our minds and eyes wide open to the possibilities and our curiosity keen to know answers. Every day can be a learning experience just as reading your post and preparing this extended comment has been for me.

 

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Crystal Art

While working on a CD for a choir, I had the television on in the background. I stopped work to look at one segment of the show because it was showing how to paint with crystals. I missed all the details but was able to search the internet and here is what I found...

You will need an adult to help you and...

epsom salt

hot water

food colouring

containers for your mixtures

spoon for stirring

paintbrush

art paper

What you do. Remember, you will need to have an adult help because of the hot water...

1. Mix equal amounts of epsom salt and hot water in a container, adding five to seven drops of food colouring or using no colouring for clear crystals.

2. Use the paintbrush to paint the solution onto the paper but move quickly as crystals start forming as the solution cools.

3. Repeat using different colours.

4. Wait for the crystals to form and paper to dry. It could take two to three hours.

* * * * * * *

Searching the internet, I found collections of images of crystal paintings...

Crystal Art Images

To see the 2013 post where Keira left her comment and questions...

What Stone Is That?- A Follow Up Post for Keira

This photo was supplied by Mrs. Yollis and class.

This photo was supplied by Mrs. Yollis and class.

Hello Keira,

In one of your comments you mentioned you had a plethora of questions. A superabundance of questions is the sign of an inquiring mind. It seems as though your questions have turned from astronomy to geology. As before, your words will appear in bold blue text.

Since the day I found the rock that you mentioned in the post at a camping site, I have treasured it. Recently, I went camping at the same exact site, and I found many more rocks that seem to have some kind of beautiful mineral inside of it. In fact, I collected a rock that is made out of all gem. I am a little disappointed that in comments, you cannot post pictures with the text. If I could, I would take a picture of all the rocks I collected so you could see them for yourself.

You have discovered the reason this blog was formed. I also found comments on blogs generally couldn’t include photos, videos or sound and were limited to only one link. A blog allows it all providing we know about being safe online.

When I stumble upon an interesting rock, I tend to have the instinct to pick it up. I know that you probably have that same instinct too, because you are like a walking encyclopedia, always gathering up new information. I said this because I wanted to know if you have either found or bought any new rocks yet. I also want to know which one you most likely do to collect rocks: Do you buy them from rock sellers more often, or do you collect them on your own outside more?

While I have collected rocks in the field, I am unable to travel as much as I once had so these days I am more often to buy samples if I find them interesting. I have recently added some interesting stones. See if you find these samples interesting…

The first photo shows flourite (calcium flourine) crystals. The green mat they're on have 1cm squares so you can see their size. Each crystal has 8 facets (faces), i.e. they are octahedral crystals. They have not been cut. A collector was selling some of his samples at a local country show.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

In my area, different towns have markets on weekends. When visiting one, I found a man was selling geodes from Queensland. While I already had some, I was fascinated by this sample because it looks as though two fused together when they were formed perhaps 200 million years ago.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

Here is one from my collection that has been broken open. They aren't as impressive as my Brazilian geodes but I like the Australian samples because they are from home.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

I have yet a few more questions to ask you. Have you ever found a rock from a volcano? I think it would be most likely that you have because, in one of your posts, you said that you had seen a few volcanoes erupt. If, a couple months later, you had gone down to examine the area near the volcano, and you found a interesting rock, I think you would have kept it and put it in your collection. I know that if I found one, I would definitely keep it.

When collecting any stones, we must be aware whether or not we are in national parks where we are not permitted to collect stones and rocks. There are places where you can collect stones, including igneous (volcanic) rocks. When I can, I have collected stones but I have also bought many.

My favourite item from a volcanic area in New Zealand was collected by me (with permission). It was collected near a fumarole where the sulphur (U.S. spelling: sulfur) crystals were forming. Because sulphur crystals break down and lose their shine if exposed to water or moist air, the below sample has been kept in a perspex box since I found it over 30 years ago. The crystals still shine as you can see.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

I have already written a number of posts on volcanoes. Below are links to some of the first posts written for this blog back in 2012...

Volcanoes Post 1

Scree and Obsidian

Aa and Pahoehoe from Hawaii

Pumice and New Zealand Iron Sands

Geological Hot Spots

New Zealand

Final Volcano Post

Another question is have you ever been in a cave where jewels were growing naturally? I asked that question because I heard on a science show that people can explore caves with jewels in them. I doubt that you have ever been in one, but I can not know for sure until you tell me the answer. If you have been in one, what kind of minerals did you see?

A cave of jewels… what a wonderful thought reminding me of the first time I saw the 7 dwarfs working in the jewel mine in Disney’s “Snow White and the Seven Dwarfs” when I was about your age. I dreamed of finding such a mine back then but I know finding a mine with gem quality stones is hard enough without expecting more than one type of gem. A diamond mine would be nice. 🙂

Below is an item in my collection measuring 5cm diameter across the top. Unfortunately, it is only a glass replica.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

I have been in gold mines, coal mines and a couple other mines but the closest to a jewel mine would have been an opal mine. There are mines all over the world where jewels are found, some very unsafe for the miners. I only enter mines welcoming visitors on guided tours.

Perhaps Australia’s most famous jewel mine is the Argyle Diamond Mine in Western Australia. It is an open cut mine where they dig down making valleys not dig tunnels.  Here is a link to their website.

Argyle Diamond Mine

You might know diamonds can be different colours other than clear. Argyle’s most famous colour is pink. Click on the link below to see some of the colours in Argyle diamonds…

Argyle Pink Diamonds

This is the last question I have before the last question I want to ask you. I want to ask you if you have ever mined any type of mineral. If so, what did you mine?

When out hunting for stones, I often have my geologists hammer with me. The pointy end is use to chip into rocks and the flat end to break rocks. You could say I have used this in mining in a small way. The picture is below…

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

I have also panned for gold in old gold fields and hunted for rocks, crystals and fossils in many locations.

Gold

Some of this sample has been panned by me. Much was bought.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

I bought this sample of gold in quartz from a place called Hill End where there was an active gold mine. I have been in a mine in the area but not the active mine.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

A gold nugget from New Zealand, it is about 1.5cm across.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

Fossils

The two fossils below were found by me at a rock fall site many years ago. The first shows a fossilised leaf and the second is part of a fossilised tree trunk.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

 In this sample I picked up, you can see shells in the stone. Rather than fossils, they are still real shells embedded in stone.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

I picked up the following shell embedded in rock from an open cut mine.

Shell 30,000 years old

Finally, I want to ask you if you have ever cut a rock open and discovered gems inside?

A gem is a stone used in jewellery so it can be anything from quartz to diamonds, emeralds and rubies. I have found quartz and amethyst in rocks as well as in rivers where they have been washed. Some of my stones are of gem quality but I have never found anything really valuable.

This quartz crystal sample might be of gem quality in part if it was cut but I like it as it is.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

As you said in your post, you do not have a diamond cutter, but have you ever used one? If so, was it hard to cut the stone open?

I have seen them used but I haven’t used one. It’s a skill to be able to cut a stone well. I have stones I collected so I could use them if I had access to a diamond saw. They are known as chert and are reasonably easy to cut and polish but aren’t worth much. My samples have colour bands through them so they might look good cut, shaped and polished into cabachons.

Diamonds are not made into cabachons nor are other gems such as emerald and rubies. They are faceted. This means they are cut and polished to have faces. Turquoise, agate and opal are examples of stone often made into cabachons. Look at the images of assorted cabachons below.

CABACHON SAMPLES

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

A diamond saw is used on most stones, diamond being the hardest stone we can find. It uses a special saw blade embedded with diamonds. Before you think this is a waste of diamonds, most diamonds found are not of gem quality. They are industrial quality. I have seen websites selling these low quality diamonds for as little as $120 to $180 per kilogram.

If you have never cut a stone open, would you ever like to cut one of your stones open?

While I would like to be able to cut my own stones, time to do so and the money to buy the equipment means this isn’t possible. I have broken open some samples to look inside but mostly I keep them as I found them. One of the problems with being interested in so many things is finding the time to do them all but it is fun doing what I can.

Keira also had questions on a geology post. Here are some possible answers...

Curious Keira Asked About Geology

4 Comments

Keira left a quality comment on a blog post.

What Stone Is That? - for Mrs. Yollis and class

Hello Keira,

Your rock has certainly caused much thought as we have tried to uncover its secrets. Science can be like that, a chance to uncover mysteries. After leaving a reply to Heather's quality comment, I found you also left a quality comment.

Here is a link to the information I shared with Heather...

What Stone Is That? - A Follow Up Post for Heather

This photo was supplied by Mrs. Yollis and class.

This photo was supplied by Mrs. Yollis and class.

Now for your comment...

Do I know why your rock looks amber on the outside?

From the picture, I'm not able to see the amber colour on the outside. It may be just the remainder of stone or dirt once surrounding your rock. Look at these photos. The first shows a collection of four geodes, one complete. The second shows a geode containing amethyst (mauve quartz). If you look closely, you can see the colours on the outside aren't always the same as the colours inside the geodes. There are other minerals probably once from the surrounding rock. Did you notice one in the top photo has a yellowish outside?

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

It's also possible some citrine quartz crystals might have started to form on the outside. The picture below shows citrine quartz in the paler rock. We can't be certain unless your rock is checked but, no matter what is on the outside, I found your rock very interesting.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

About Galena

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

I like your description of galena. It does look a little like tinfoil. Tin (Sn) is an element as is the metal in galena. Galena is lead sulfide (PbS). It's where we get much of the lead (Pb) we use. Below is the heaviest sample in my collection. It's not the biggest in size but weighs 2500g (5.5lb). The gold coloured part of the sample is iron pyrite. It also contains zinc (Zn) but is mostly lead (Pb) in the form of galena. The small whiter patches on the lower left are quartz. The sample comes from one of my state's major mining areas, Broken Hill.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

Click on GALENA and it will take you to a Wikipedia page on galena. You will see where it can be found around the world and in U.S.A..

How do you find out all these facts?

I have been interested in very many subjects over the years. When I see something interesting, I sometimes remember facts and information I think might be useful in an extended comment. As I write, I start looking for more information and learn as I go.

For geology, I have assorted books and I can also search online. I always try to check the information I share on blogs because I'm not an expert in any area. Like you, I'm a learner. I've just had more time to learn.

Where did you get all these rocks?

Most of the samples I have were bought in rock shops with only some being collected by me. Many come from countries I have never visited. As an example, the big round geode and the one cut in half beside it are from Brazil. While it can be fun searching for your own samples, collectors often have to buy samples of rarer minerals or ones found in other countries. I have been collecting stones and crystals since I was about your age. It's just a matter of keeping your eyes open  in many cases. Look at these...

The first sample caught my attention because I could see crystals in it. Could it be a geode waiting to reveal something special inside? Perhaps I might one day break it open to find out.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

This one is a geode from Queensland. You can see the crystalline mass in it. Perhaps cut and polished, it could look very good but I like it as it was found.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

This rock was very interesting when I found it. You can see it also has a yellowish exterior like your rock but some chips broken off the rock have revealed what could be agate. I suspect this sample could look very impressive if cut and polished. The material inside might look like your rock.  As I don't have access to a diamond saw to cut it, I keep it as it is, a mystery.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

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A Hand Painted Geode?

"...Geodes, the first one looks interesting to me. The middle almost looks like it is hand painted. Was the middle polished or was it like that when you discovered it?"

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I must say this sample looks as though it's the work of an artist. What I believe has happened is, as different minerals have mixed as the crystals formed in a space, different colours were formed. In this geode, crystal growth has filled the space.

I saw this cut and polished sample in a rock shop. It was the pattern you noticed that caught my attention.

In the middle of the rock that is cut open it looks like there is a little nook. Am I right?

 

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

You are a very observant person. There does seem to be a little nook in the cut rock but it is due to the way the crystals have grown inside the geode. Along the inner cut edge, you can see the crystals aren't even like a circle but have some areas thicker than others. This unevenness means some areas extend out over the others. Sunlight on them leaves a shadow below. In the shadowed area, the crystals look much like the small crystals in the middle.

Considering your curiosity and interest in rocks, I hope you keep learning and discovering. A mind with curiosity can be a very powerful learning tool.

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I received a question via Twitter...

Do you know what kind of stone this is ?

There was the below photo attached to the tweet...

This photo was supplied by Mrs. Yollis and class.

This photo was supplied by Mrs. Yollis and class.

I like a challenge and, although not always successful, finding an answer. I have an interest in geology but l find I know a little about many things but not a lot about anything. Without being able to hold the rock and look more closely, and without expertise, my first stop was to look more closely at the photo. Here's what I noticed...

The stone was white to bluish-grey.

Breaks around the edges looked a little like they might break off in flattened, sharp edged pieces.

There appears to be an inner border (lining) on the stone.

I wanted to see the border closer so I enlarged a section of the photo (below). I also enhanced contrast and colour a little.

This photo was supplied by Mrs. Yollis and class.

This photo was supplied by Mrs. Yollis and class.

 I now noticed there seems to have been some fine layering around the edge of the stone up to the border. Layering can mean sedimentary rock but, it can also be a sign of a space in rock filling with crystals. I had seen something like this before. I probably have a few hundred small mineral samples in my collection so I started to search. Firstly, a display of stones I had used with classes over the years...

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

A few of these showed some of the features I was looking for, especially calcite, agate and quartz.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

This reminded me of larger samples I had in my minerals database, I found items 41 and 46. They are listed as "Quartz - Chalcedony - Agate". They are examples of silicon oxide (SiO2).

The first sample has been cut and polished. The layering towards the outer edge is easy to see. There are small quartz crystals in the centre of the sample. I have seen this in other of my samples where inner spaces aren't completely filled. See geodes and the additional photos at the end of this post.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

The second sample was a piece broken off a larger sample and only had a low sheen.

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Schools and students have permission to use this graphic for non-commercial, educational purposes.

Without being able to hold and examine the sample in Mrs. Yollis's class, I suspect they have a sample of agate or chalcedony. Remember, I am only interested in geology and not an expert so I'm really only guessing.

How is it formed? My database explains it this way...

A concentric, banded, fibrous variety formed by precipitation from watery solutions in rounded cavities in lava rocks (geodes), sometimes with beautiful clusters of rock crystals or amethyst at the centre.

From my collection, below are photos of geodes. Most have been cut and one polished to show the interior.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

The last photo shows one cut sample and an uncut geode beside it. What's inside the uncut geode? I can tell you it is about the same size as the cut geode if it was whole. This means the uncut geode should be about twice the weight of the half but it is around three times the weight of the half. It may be solid or have a small central cavity. It could be very beautiful or possibly plain inside. We'll never know because I won't have it cut. I like a little mystery in the world. 🙂