12 need to know igneous rocks Flashcards
granite is usually what colour
light coloured
granite is usually what grained
medium to coarse
granite is usually made of
quartz, orthoclase, muscovite, biotite, hornblende
granodiorite has more ………. than granite
plagioclase feldspar
granodiorite is usually darker than granite because
it has abundant biotite mica and hornblende
biotite mica is …………..than muscovite mica
darker
in granodiorite the lighter minerals are
quartz and feldspar
in granodiorite the darker minerals are
hornblende or biotite mica
rhyolite is basically a
fine grained granite
rhyolite often contains ………. showing rapid cooling
glassy bits and voids
rhyolite is very often …….. with the minerals aligning themselves
flow banded
pumice has loads of ………. which make it float
vesicles
pumice has the same composition as
rhyolite
obsidian is formed in about
a few hours
pegmatite is classified as a
intrusive igneous rock
pegmatite has what type of grain
coarse grained
pegmatite is any rock that has unusually
large crystals
crystals of pegmatite are usually a few
cms or metres
diorite is simular to
granite
diorite has a……….. colour
salt and pepper
diorite is distinguished from granite by having ….. …
no visible quartz
andersite is usually what colour
grey to black
andersites have crystals mainly made of
plagioclase feldspar, and pyroxene
quick opportunities meet brown hares. is for remembering what
the minerals in granite
gabbro has what grain
course grained
gabbro is heavier than
granitic rocks
gabbro is usually ………. coloured
dark
gabbros normally has no …….
quartz
is dolrite intrusive or extrusive ?
intrusive
