What Stone Is That? – A follow up post for Keira

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.

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.

About Galena

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.

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.

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.

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.

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 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.

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 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.

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

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?"

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.

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?

 

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.

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.

4 thoughts on “What Stone Is That? – A follow up post for Keira

  1. Keira

    Dear Mr. Mannell,

    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 can not 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.

    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?

    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.

    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?

    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?

    Finally, I want to ask you if you have ever cut a rock open and discovered gems inside. 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? If you have never cut a stone open, would you ever like to cut one of your stones open?

    Sincerely,
    Keira

    Reply
    1. rossmannell

      Post author

      HI Megan,

      With so many rock types, it would be hard to list them all. The post was showing some of interest to Keira. Rock collecting can be fun, especially when you find a really interesting one. 🙂

      Ross Mannell

      Reply

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