Edge sharing coordination tetrahedra ataoxc 211

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Unformatted text preview: 威德_Lecture 12 sulfates 國立成功大學地球科學系 礦物學(一) 江威德 13 2009/11/24 Pauling’s Rules 國立成功大學地球科學系 Rule 5: The principle of parsimony. Structural (結晶構造簡單化)。 ↓ The number of essentially different kinds of constituents in a crystal structure tends to be small. ◎ A large number of different kinds of coordination polyhedra large number of different kinds of coordination polyhedra in in given structure tends to decrease its stability. ◎ Only 2 or 3 different types of polyhedra are found in most minerals. ◎ The number of crystallographically different sites tends to be small, and is in small integer ratios to each other. small, A tendency with many exceptions. 國立成功大學地球科學系 礦物學(一) 江威德 Tourmaline group (5 different polyhedra) NaIX(Mg,Fe,Li,Al)3VIAl6VI[Si6IVO18](BIIIO3)3[(O,OH,F)]4 An exception to the Pauling’s 5th rule 國立成功大學地球科學系 礦物學(一)...
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