Roan
has rocks in the head
Member since January 2008
Posts: 600
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Post by Roan on Sept 29, 2008 13:11:27 GMT -5
What exactly is the difference between these rocks? Do they just have different inclusions?
Thanks, Eileen
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Post by akansan on Sept 29, 2008 17:04:43 GMT -5
Lapis and Sodalite are two totally different things. Technically, Sodalite is a mineral by itself and Lapis is a rock type made of three different minerals (Calcite, Lazurite, Pyrite).
Green Quartz and Aventurine are a lot closer - Aventurine is basically quartz with mica inclusions (thus the shimmer).
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Roan
has rocks in the head
Member since January 2008
Posts: 600
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Post by Roan on Sept 30, 2008 0:23:15 GMT -5
Ah! I didn't realize that Lapis and sodalite were two different things. They seem so similar. I thought it was the white inclusions (calcium?) versus the pyrite in lapis.
What gives the green quartz the green color?
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Post by akansan on Sept 30, 2008 7:13:10 GMT -5
That's okay - sodalite as a complete mineral was news to me! From what I could tell, the entire piece, white, blue, whatever, is just sodalite!
As for the green in quartz and aventurine, I know I've read what makes the rocks the color they are, but besides copper and iron, I can't remember the other changers (iron = red, copper = green). I don't think copper is the cause of the green in green aventurine and green quartz, so there's probably another one out there that turns things green...
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Post by sitnwrap on Sept 30, 2008 8:08:14 GMT -5
After reading this thread (thanks for the info as I also thought Lapis and Sodalite were of the same family of minerals) I got curious about Green Quartz so I did some digging. Apparently the green in Quartz is caused by Chlorite. I also found a neat site giving brief descriptions for a lot of minerals. I found it interesting so here's the link. maine.gov/doc/nrimc/mgs/explore/bedrock/2-lights/glossary.htm
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Post by sparkles on Sept 30, 2008 10:41:28 GMT -5
Ah, I just spotted this one and thought I'd add my understanding to the pot. Indeed the green in green quartz is Chlorite, it's the same stuff that forms thread crystals in green moss agate, but in Aventurine the green is imbued by the fuchsite mica flakes that give it the sparkle effect - aventurescence. Green quartz grows in crystal forms, however aventurine is a metamorphic material composed of tiny quartz grains compressed in to a quartzite rock with various inclusions, the green fuchsite mica flakes causing the characteristic sparkly bits. Cheers, Sparkles
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Roan
has rocks in the head
Member since January 2008
Posts: 600
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Post by Roan on Oct 2, 2008 5:26:14 GMT -5
Thanks!
I bought some really, really tiny green quartz I bought off my source and it looks like there is some aventurine mixed in the batch. When the rocks are that small, it can be hard to tell what's what.
Eileen
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Oct 2, 2008 21:00:39 GMT -5
So, Sparkles, is your posted photo aventurine? I have some of the "green with sparkles" rock in a mixed batch that I assume it also aventurine. Here is a pic from before the final polish:
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Roan
has rocks in the head
Member since January 2008
Posts: 600
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Post by Roan on Oct 2, 2008 22:52:45 GMT -5
Yep, that's aventurine. I have a lot of it tumbled as well and a bag of yellow that I'm going to smash up to make a yellow tree with.
Green quartz, from what I've gotten, looks like it has tiny "streaks" of green in it, but it's not sparkly. More like a solid color in its own right. Don't forget I'm working with flattish pieces that are around 7mm in size -- very small -- so I see it up close. In the larger pieces the green looks like it's one solid color throughout the entire rock, but I suspect it's all those green "threads" or "streaks" of chlorite are abundant and close together enough to make it look solid.
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