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