The specimen library

A starting field guide to the rocks, minerals and fossils people find most often — and the landforms that shape the ground beneath them. Spot the tell, then bring your own find to the studio for a full reading.

Read your own stone

Granite

Igneous

Coarse pink-and-grey speckle of slowly cooled magma, deep underground.

How to tell: Interlocking crystals big enough to see; scratches glass.

Basalt

Igneous

Dark, dense, fine-grained lava that cooled fast at the surface.

How to tell: Heavy for its size; may tug a magnet.

Limestone

Sedimentary

Pale rock built from ancient sea-floor shells and skeletons.

How to tell: Fizzes with a drop of weak acid; often holds fossils.

Quartz

Metamorphic

Glassy six-sided crystals grown from silica-rich fluids.

How to tell: Hardness 7 — scratches glass and steel.

Pyrite

Metamorphic

Brassy metallic cubes — the classic 'fool's gold'.

How to tell: Greenish-black streak; too hard to be gold.

Amethyst geode

Metamorphic

A gas cavity slowly filled inward with purple quartz points.

How to tell: Hollow and light; crystals line an open cavity.

Ammonite fossil

Biogenic

The mineralised coiled shell of an extinct sea creature.

How to tell: Tight ribbed spiral with internal chamber walls.

Landforms and how they form

Limestone gorge landform — Limestone gorge
A river slowly dissolving and cutting down through layered soluble rock.

Volcano landform — Volcano
Layered lava and ash built up by repeated eruptions from below.

Coastal sea cliff landform — Coastal sea cliff
A retreating rock face undercut and shaped by wave erosion.

Identifications and geological interpretations are educational estimates and may be wrong. Geode is not a licensed geological, geophysical or geotechnical service. Fieldwork content is general information only and does not encourage entering dangerous locations (cliffs, tidal zones, quarries, mine workings, private land). Follow local law and collecting ethics.