Bioclastic limestone

Oolitic limestone

Calcite crystalline limestone e.g. Carboniferous Limestone

Conglomerate

Calcareous sandstone

Greywacke sandstone

Micaceous sandstone or Flagstone

Feldspathic sandstone or Arkose

Coal

Breccia

Dolomitic limestone e.g. Magnesian Limestone

Sedimentary Rocks

Flint & Chert Chalk

Rhyolite

Micro-granite

Andesite

Obsidian Basalt

Micro-diorite

Dolerite

Granite

Igneous Rocks

Pegmatite

Peridotite

Gabbro

Diorite

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Crystalline?

yes

reacts with acid

slow reaction, no fossils

rapid reaction,, may have fossils

Mudstone

Shale

Marl

Siltstone

no

Quartz arenite

very hard, very fine grained, may appear finely crystalline

bedding & other sedimentary structure

clastic or fragmental

Sedim

entary

much plant material, dark in colour

abundant fossil fragments

whole rock reacts with acid

grains like fish roe

earthly and white

fossils may be present

Metamorphic Rocks Metaquartzite Granulite Hornfels

Migmatite

Gneiss

Schist

Phyllite

Mylonite

Slate

light in colour

fissile

massive

reacts with acid

very fine grained 2mm

Study grain size

medium clasts < 2 mm & > 0.06 mm, arenaceous

fine clasts < 0.06 mm, > 0.004 mm

quartz and feldspar clasts

splits easily along bedding & micaceous

lithic & mineral grains in muddy matrix

matrix reacts with acid

intermediate

glassy

intermediate

light colour and density

intermediate colour and density

fine grained < 1 mm

medium grained 1 - 5 mm

Grain size

v. coarse > 3cm

v. dense

dense

course > 5 mm

light colour

Rock identification chart for identifying common rock

types based on simple observation and tests on

hand specimens

dark

dark

dark

no lineation or banding

lineation or banding visible

sugary texture

Marble calcite

main mineral

coarse

grain size

quartz pyroxene & feldspar

medium

splintery

very fine grained

fine

medium

medium to coarse

coarse

splits easily

pale in colour

Green sheen on cleavage surface

banded

streaky