Browse Items (3 total)

Formula (Mg,Fe2+,Fe3+,Mn,Al)12[(Si,Al)8O20](OH)16 Structure Sheet silicate Crystal System Crystal system: monoclinic (+) (-) Physical Properties Colour in hand specimen: green Cleavage: one, good Hardness: 2-3 Optical…

Formula (Mg,Fe,Ca)3Al2Si3O12 Structure Orthosilicate Crystal System Crystal system: cubic Physical Properties Colour in hand specimen: typically redCleavage: noneHardness: 6-7.5 Optical Properties Colour in plane polarised…

Hand Specimen Fine-grained, blue-green, sedimentary texture. Slaty cleavage. Some patches of lighter and finer-grained material. Thin-section Slaty cleavage due to the alignment of chlorite and muscovite. Cross-cut by the blobs of the…