Rock Identification

Layers

Lighter

Brown

No visibly darker layers

Sandstone

Visible darker layers

Gneiss

White

Dolostone

Black/grey layers

Marble

Spotted

Smaller spotted grains

Granite

Larger spotted grains

Pegmatite

Pebbles

Conglomerate

Salt and pepper appearance

Gabbro

Holes

Pumice

White/Grey

Translucent

Quartzite

Opaque

Limestone

Layers

Not Glassy

Brown

Schist

Grey

Shale

Glassy

Obsidian

No Layers

Darker

Hardness

Can not be scratched by a penny

Basalt

Can be scratched by a penny

Slate

Large spotted grains

Andesite

Small spotted grains

Diabase

Lighter

Brown

Rhyolite

Grey

Chert