The field guide
Rock identification guides
Start with the question you have about your find. Each guide explains which clues help and where a home check stops, so you know when to ask someone who can examine the specimen in person.
Compare lookalikes
Quartz vs calcite
Use hardness and cleavage to tell two clear, glassy minerals apart.
Quartz vs glass
What crystal structure, hardness and bubbles can and can’t tell you.
Agate vs jasper
Compare banding and translucency, and why a glowing edge doesn’t settle it.
Pyrite vs gold
Which clues separate fool’s gold from gold, and which tests mislead.