Browse Items (3 total)

Formula K2(Mg,Fe2+)6-4(Fe3+,Al,Ti)0-2[Si6-5Al2-3O20](OH,F)4 Structure Sheet silicate Crystal System Crystal system: monoclinic (-) Physical Properties Colour in hand specimen: brown or black Cleavage: one, good Hardness: 2-3 Optical…

Formula K2Al4[Si6Al2O20](OH,F)4 Structure Sheet silicate Crystal System Crystal system: monoclinic (-) Physical Properties Colour in hand specimen: colourless Cleavage: one, good Hardness: 2.5-3 Optical Properties Colour in plane…

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…