FIELD STEP
Expose a fresh surface
Weathering can disguise colour and lustre. Use an existing broken edge where possible.
A disciplined process.
More reliable observations.
Follow a repeatable six-stage field procedure designed to reduce misleading indicators and preserve sample integrity.
FIELD STEP
Record lustre
Judge how the surface reflects light before recording its colour.
FIELD STEP
Make a streak
Rub the sample across unglazed porcelain and record the powder colour.
FIELD STEP
Bracket hardness
Test against known objects: nail 2.5, copper 3, glass 5.5, steel 6.5.
FIELD STEP
Read the break
Repeated smooth planes indicate cleavage; irregular surfaces indicate fracture.
FIELD STEP
Run special tests
Use a magnet where appropriate. Use dilute acid only with protection and permission.
Small tests.
Sound judgement.
- Wear eye protection around fresh or brittle edges.
- Never taste or inhale mineral powders.
- Do not acid-test valuable or hazardous material.
- Wash hands after handling unknown samples.