EAS201 Lecture Notes - Lecture 3: Phenyl Salicylate, Chemical Substance, Triclinic Crystal System
20 Sep 2016
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Definition: a mineral is any naturally formed, solid, chemical substance having a specific composition and characteristic crystal structure. This definition excludes substances produced in the lab, liquids and gases, and amorphous materials. Building blocks: atoms (smallest individual particles that retain all of the properties of a given chemical element) A variety of the element that has a slightly different mass. Dramatic increase/decrease in the quantity of these isotopes. The weak van der waals bonds are easily broken, so when you rub graphite between your fingers, the covalently bonded sheets of carbon readily slide past one another. 7 crystal systems: (32 classes, 230 space groups) This is classical crystallography which possesses only 2-, 3-, 4- and 6-fold rotational symmetry and translational symmetry. Angles between faces (interfacial angles) are constant for specific minerals. Different habits depending on crystal, but angles between faces are always the same within specific mineral group. Breakage in preferred directions along reflective planar surfaces.
