An absolutely pristine ball of California artinite (Zinn Coll. #1077). Artinite is a rather rare and lesser-known carbonate mineral (though it LOOKS a lot like some well-known zeolite minerals) that sometimes forms these perfect balls of radiating, fibrous crystals. Its chemical formula is Mg2CO3(OH) 2 + 3H2O (Hydrated Magnesium Carbonate Hydroxide). HUGE ball of artinite here!