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Mineral Monday: Mica

Vanessa the velociraptor helps demonstrate the transparency and cleavage planes of mica

Welcome to another Mineral Monday! Today we’re all about Mica. When I was a kid I used to spend a lot of time outside playing in creeks, and I would see lots of tiny sparkles on the creek bed- looking like fairy dust or gold. When I would reach for them, though, the beautiful sparkles would float downstream- a good sign that it wasn’t gold which is far denser. Instead it was mica- a soft flaky mineral that shines like gold or quartz. It’s unique in that it forms in long broad plates all stacked on top of each other, which results in a very distinctive cleavage.

For my non-geo nerd readers; I’m not talking boobs.

Cleavage in mineral terms is the way a rock or mineral breaks. Whether or not it breaks in a curved or straight line is how it fractures, but the direction in which the breaks go and the angle of the break defines the cleavage- and only some minerals have distinct cleavage planes. Mica has just the one horizontal cleavage plane, which means you can peel it into thin shining translucent layers, great to look through or make into jewelry!  In addition to being intriguing mica is something that you probably use every day, on your face or teeth.

Mica’s soft, shiny, and non-toxic properties means that it is perfect for being the shiny bits in toothpaste and natural makeup varieties. Next time you’re in the health and beauty section of the supermarket check out the inactive ingredient section on the back of toothpaste boxes. You just might find some minerals there.

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