QUESTION: "I read that quartz is the most abundant mineral on earth? So how come I see more agate and jasper than quartz? What's up with that?"
MY ANSWER: The reason you apparently see more agate and jasper than the most abundant mineral quartz is because agate and jasper are quartz. Yes! Agate is a translucent and often striped chalcedony quartz, which is a microcrystalline quartz. Jasper is an opaque chalcedony quartz, another microcrystalline quartz variation. Agate and jasper are actually unofficial mineral names, although they're used all the time to give people a better idea of what it is. After all, a clear quartz crystal and a piece of agate don't really look much like the same type of stone.
Originally posted on CrystalsAndJewelry.com in 2005. Updated January, 2013.