About RockIDGuide
RockIDGuide is the field geology companion: what the specimen is, the tests that prove it, and the lookalikes that fool everyone once.
RockIDGuide exists because "what is this rock?" deserves better than vibes — hardness, streak, luster, and cleavage are measurable, and twenty common species cover most of what people actually find.
RockIDGuide is organized so you can browse by collection or jump straight to an entry. Each entry keeps to the same shape — the facts at a glance, then the plain-language detail — so comparing two entries takes seconds, not tab-juggling.
The project is independent and ad-supported. We are not affiliated with any brand, agency, or organization whose work we reference. Corrections and suggestions are genuinely welcome via the contact page.
What makes RockIDGuide different
- Your numbers never leave your browser. Every calculator on RockIDGuide runs entirely on your device. We never see, store, or transmit the figures you enter — there are no accounts and no server-side processing of your inputs.
- Published methodology. Each calculator page explains the exact formula it uses and the assumptions behind it, so you can check our work or reproduce it in a spreadsheet.
- Free, forever, without a paywall. RockIDGuide is supported by advertising. There is no premium tier, no email gate, and no upsell.
Independence
RockIDGuide is an independent educational project. We are not affiliated with, endorsed by, or acting on behalf of any government agency, lender, insurer, or the organizations whose formulas and public data we reference (such as published field guides and reference literature). All trademarks and referenced standards belong to their respective owners.
Questions, corrections, or suggestions are genuinely welcome — get in touch.