ERS120H5 Lecture Notes - Lecture 6: Mica, Orthoclase, Conchoidal Fracture
22 Jan 2016
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Document Summary
Start with the basic building block: silica tetrahedra. Covalent bond: si and o share electrons to become a stable sio4 silica. The fundamental building block of a silicate mineral is the silicon-oxygen tetrahedron. Oxygen occupy the corners of the tetrahedron, and silicon lies at the center. Geologists portray the tetrahedron in a number of different ways. Some properties: 6-sided crystal form, uneven fracture, hard, strong, durable. Earth"s crust: oxygen takes up most and least is other oxygen, silicon, Aluminum, iron, calcium, sodium, potassium, mg, other (most space to least) If you smash it on the floor it will not fracture, it will cleave (2 cleavages, 90 degrees) On the face of it you can see the single chains. Double chains: to separated chains and then points connecting one another from the middle. 2 clevages: 60 and 120 degrees going to break 60 and 120 degrees angle. The top one: biotite best way to memorize it that it"s black.
