Amphibolite is a mafic
It forms in moderate
temperatures but under high pressures.
It mostly consists of
minerals, such as hornblende, actinolite, plagioclase feldspar, mica,
pyroxene, calcite and sometimes large garnets.
It is one of the
facies, representing the composition of minerals that will form in any
rock in similar pressures, temperatures and depths.
By Ron Schott via Flickr.com
Amphibolite forms from mafic igneous or sedimentary rocks such as
greywacke, dolomite, andesite, basalt, diorite, gabbro.
is a very hard rock, used in road building. It is medium to coarse
grained, crystalline rock that can be greenish, grey or black in colour.