jahzilla1
off to a rocking start
Member since July 2020
Posts: 5 
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Post by jahzilla1 on Jul 18, 2020 18:50:25 GMT -5
aventurine has aventurescence; aventurine with no aventurescence = green quartz linkprasiolite is the generic name for any green quartz, but since like 1950 all natural green quartz in the world comes from Brazil. and all natural green quartz is in crystal form, not like the block he showed. So can't be green quartz, not in that form |
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gemfeller
Cave Dweller 
Member since June 2011
Posts: 4,059
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Post by gemfeller on Jul 18, 2020 19:25:10 GMT -5
aventurine has aventurescence; aventurine with no aventurescence = green quartz linkprasiolite is the generic name for any green quartz, but since like 1950 all natural green quartz in the world comes from Brazil. and all natural green quartz is in crystal form, not like the block he showed. So can't be green quartz, not in that form You are correct about prasiolite being green quartz. But there seems to be some confusion in this thread between single-crystal quartz like amethyst or quartz crystals, and quartzite (aventurine). Some natural crystalline prasiolite is mined but it’s quite rare. Most of the prasiolite on today’s market is amethyst that’s heated and irradiated to induce the green hue. That’s why the term “greened amethyst” is more accurate that “green amethyst,” which is often used. Quartzite is a metamorphic rock which was originally pure quartz sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression. It can be a very attractive stone when it is colored by inclusions like fuchsite (a green chromium-rich variety of muscovite mica) which gives quartzite a pleasing green color. If the quartzite is semitransparent to translucent, the flat flakes of mica can reflect light to produce a glittering luster that's called aventurescence, ergo aventurine. |
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Post by hummingbirdstones2 on Jul 19, 2020 10:01:38 GMT -5
gemfeller is right about the "Phenomenal Gems" book. It's a good resource.
Hearty second also on the comment about "aDventurine".
Would recommend that anyone new to rock-related pursuits buy reference books. Much better than chasing down answers to individual questions online.
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