1. Ge 101. Introduction to Geology and Geochemistry Lecture 2 Crystal Structure of Minerals

2. Image 2.1

3. MineralChemical formula Cleavage planes and number of cleavage directions Silicate structure Specimen 1 plane Isolated tetrahedra 2 planes at 90° Single chains 2 planes at 60° and 120° Double chains 1 plane Sheets Olivine Pyroxene Amphibole Micas Feldspars 2 planes at 90° Three-dimensional framework (Mg,Fe) 2 SiO 4 (Mg,Fe)SiO 3 Ca 2 (Mg, Fe) 5 Si 8 O 22 (OH) 2 Muscovite: KAl 2 (AlSi 3 O 10 )(OH) 2 Biotite: K(Mg, Fe) 3 AlSi 3 O 10 (OH) 2 Orthoclase feldspar: KAlSi 3 O 8 Plagioclase feldspar: (Ca, Na) AlSi 3 O 8 Image 2.2