Almost 30 million years ago, an asteroid or comet impact fused Saharan quartz grains into desert glass.
Topaz is the hardest silicon-based mineral, and its clarity and beautiful color make this a beautiful and very popular gemstone. Topaz got its name from
Air bubbles and other meterial trapped in mineral grains tell scientists many things about the Earth and its history.
Microphotgraphy using polarized light yields beautiful art. It also is very helpful in learning more about a gem.
We’ve looked before at how sapphires for. Now let’s check out Montana sapphires – North America’s biggest known deposit of gem-quality stones – and see how gemologists manage to get every bit of color they possibly can from each sapphire – even the green ones!
Diamonds aren’t the only mantle-associated gems. Most of the upper mantle is made out of peridotite, a combination of olivine and pyroxene. It is named after the very famous gemstone it contains–peridot.