I am the most common of the feldspar minerals, which, as you know, make up the bulk of the Earth’s crust. So without us, and me in particular, you’d be standing on pretty shaky ground. My name is derived from the Greek for “oblique fracture” (in reference to my two cleavage angles), and unlike my glassy cousins, the potassium feldspars, I am known for my high refractivity. Yes, light — and time — slow when they meet me.
Who am I?
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