Overview
A mineral is a naturally occurring solid with a definite chemical makeup and crystal structure; a rock is a mixture of one or more minerals. You can identify most common specimens with a few simple tests: color, luster (metallic or not), hardness (does a steel knife scratch it?), and the shape of any crystals.
This guide covers the minerals and rocks you are most likely to find, from feldspar and quartz to the "fool's gold" that fools beginners. Photograph your specimen from a couple of angles and use the app to help confirm what you have found.
Key Species to Know
Quartz
Quartz
One of the most common minerals — glassy, hard (it scratches steel), and often clear, white, or smoky, with six-sided crystals when well formed. Breaks with curved, shell-like surfaces rather than flat faces.
Feldspar
Feldspar
The most abundant mineral group in the crust, usually pink, white, or gray with a slightly-less-than-glassy luster and flat cleavage faces that catch the light. A main ingredient of granite.
Granite
Granite
A coarse, speckled igneous rock made of interlocking quartz, feldspar, and mica crystals big enough to see. The classic "salt-and-pepper" building and countertop stone.
Muscovite Mica
Muscovite
A pale, silvery mineral that splits into thin, flexible, transparent sheets and sparkles in granite and schist. Peels apart in flakes with a fingernail.
Calcite
Calcite
A soft mineral (a knife scratches it easily) that fizzes in weak acid and often forms clear rhombohedral crystals. The main mineral of limestone and marble.
Pyrite
Pyrite
The famous "fool's gold" — a brassy, metallic mineral that forms cubes and is much harder and lighter-streaked than real gold. Leaves a greenish-black streak.
Seasonal Guide
- Carry a hand lens, a steel knife or nail for a rough hardness check, and a small bottle of vinegar to spot calcite (it fizzes).
- Wet a specimen to bring out its true color and luster.
- A streak plate (unglazed porcelain) reveals a mineral's true powder color, which is often more reliable than surface color.
Safety Reminder
This is an identification guide only. Collect responsibly: get permission on private land, follow the rules on public land (collecting is prohibited in national parks), and never hammer at unstable slopes or road cuts. Wear eye protection if you break rock.
Identify it instantly
Found something and not sure what it is? Point your camera with Spotter and get a species identification in seconds — with detailed reference info and species notes.