About RockFinder
RockFinder helps curious people put a name to the rocks, minerals and crystals they find, right from their phone.
Why we built it
Most people who pick up an interesting stone on a hike, a beach or in the garden never find out what it is. Field guides take practice, and rock identifier apps often want an install, an account and a subscription before they'll tell you anything. RockFinder works in your browser: take a photo and get an answer in seconds.
How it works
When you take or upload a photo, it's shrunk to a sensible size on your phone and sent securely to Google's Gemini AI, which looks at color, grain size, crystal shape, luster and layering. It returns its best identification, how confident it is, and the details you see on the result: hardness, what the rock is made of, how it forms, a rough value range and a few facts.
Every result also includes a simple test you can do yourself, like a scratch test or a few drops of vinegar. A photo can't feel hardness or check for fizz, so a quick test is the best way to confirm the ID.
How accurate is it?
For common rocks and minerals photographed clearly in daylight, it's right most of the time. It's less certain with rare minerals, rocks made of many minerals, polished or dyed stones, and blurry or dark photos. That's why it always tells you its confidence and lists other things your rock could be.
RockFinder is a learning tool, not a professional appraisal. For anything you think might be valuable, like a possible meteorite, gold or a gemstone, ask a geologist, a natural history museum or a local rock and mineral club. Our guide Is my rock valuable? explains how.
Learn more
Our guides cover how to identify rocks with simple at-home tests, the most common rocks and minerals, and how to tell look-alikes apart.