GCSE Identifying Rocks and Textures under the Microscope
oolitic limestone
a sedimentary rock made of spherical grains of calcite with a calcite cement
well sorted, well rounded
state the grain shape and sorting shown by this sedimentary rock, the largest grain is 1mm in diameter
Peridotite
A coarse crystalline ultramafic (augite and olivine) rock.
marble
Contact metamorphic rock comprising interlocking crystals of calcite, largest crystal is 2mm in diameter
granite
Igneous coarse crystalline rock comprising quartz, feldspar and mica
basalt
Igneous mafic, fine crystalline rock
porphyritic
Igneous texture shown by this mafic igneous rock. Two rates of cooling
schistosity
Name the foliated texture shown by the mica in this metamorphic rock
schist
Regional Metamorphic rock comprising quartz, mica and garnet
slate
Regional metamorphic fine crystalline rock comprising chlorite and mica
greywacke
Sedimentary Clastic rock that contains rock fragments, quartz grains and up to 40% clay matrix
black shale
Sedimentary fine grained rock rich in organic matter
chalk
Sedimentary rock made up of microscopic shells of calcium carbonate viewed under an electron microscope
desert sandstone
an medium grained sedimentary rock with haematite cement
porphyroblast
name for the large garnet crystal in this metamorphic rock
equicrystalline
name the texture shown by this medium crystalline mafic rock, all the crystals are 1.0 - 1.5 mm in diameter
metaquartzite
rock comprising interlocking crystals of quartz, the average crystal size is 2mm. Equicrystalline