"Chlorite" replacing
garnet.
Micaceous flakes of Chlorite.
CHLORITE is a group name. Due to the extensive ionic substitution, a number of mineral species have been identified within the group. Most common are Penninite and Clinochlore.
The others include: Chamosite, Cookeite, Gonyerite, Manandonite, Nimite, Orthochamosite, Sudoite.
GENERAL FORMULA A4-6Z4O10(OH,O)8
A = Al, Fe, Li, Mg, Mn, Ni
Z = Al, Fe, Si
CRYSTALLOGRAPHY Monoclinic
CRYSTAL GROWTH AND HABITS Commonly in thin tabular crystals or as scaly coatings and as cavity fillings.
COLOR AND OTHER OPTICAL PROPERTIES Translucent to transparent in thin sheets; usually some shade of dark green.
HARDNESS 2 - 2.5
SPECIFIC GRAVITY 2.7 - 2.9
LUSTER Pearly on cleavage planes, vitreous elsewhere
STREAK Grayish green
BREAKABILITY Easily cleaved, perfect in one direction into flexible (but not elastic sheets).
OCCURRENCE Usually of secondary origin, derived from the alteration of garnets, pyroxenes, amphiboles and biotite. Also commonly found in schists and partially altered basalt.
MINERAL NAME From the Greek chloros for green in reference to its color.