Micaceous Diorite
Image: <a href="//commons.wikimedia.org/wiki/User:P.Lameiro" title="User:P.Lameiro">P.Lameiro</a> (CC BY-SA 3.0)
Mineral NameMicaceous Diorite
Chemical FormulaComplex silicate (aggregate of minerals)
Mohs Hardness5
Streak ColorWhite to light gray
CleavageNot applicable (rock, constituent minerals have cleavage)
FractureUneven to subconchoidal
Specific Gravity2.9
Colorsdark gray, greenish-gray, brownish-gray
TransparencyOpaque
Type LocalityGalicia, Spain
Mineral GroupIgneous rock (Plutonic)
Usesconstruction material, dimension stone, crushed stone, decorative stone
Associated Mineralsplagioclase feldspar, hornblende, biotite, pyroxene, quartz
Raritycommon
Description
This sample, identified as 'Diorita micácea' (micaceous diorite) from a historical collection, is a medium-grained intrusive igneous rock, typically dark gray to greenish-gray, with visible mica flakes.
Geological Context
Micaceous diorite forms from the slow cooling of intermediate-composition magma deep within the Earth's crust, often found in batholiths and stocks associated with convergent plate boundaries.
