Lookup
Rock and Mineral Identification Reference
Pick the rock or mineral. Each page lists the properties that identify it, the tests you can do with a fingernail, a coin, a tile and a knife, and how to separate it from what it is usually mistaken for. Photograph a fresh surface; the app suggests a name and these pages confirm it.
How to work through an unknown rock
- Hardness first: scratch it with a fingernail (2.5), a copper coin (3), a steel knife (5.5) and a piece of quartz (7); the result rules out most candidates.
- Streak next: rub it on an unglazed tile; metallic-looking minerals separate quickly on streak color.
- Then cleavage and luster: does it break along flat faces or in curved (conchoidal) surfaces; is it glassy, pearly, metallic or dull.
- Rocks are mixtures, so identify the grains you can see and the texture rather than looking for one hardness.
Minerals
- How to Identify Quartz: Hardness, Streak, Luster and Tests
- How to Identify Orthoclase (Potassium Feldspar): Hardness, Streak, Luster and Tests
- How to Identify Plagioclase Feldspar: Hardness, Streak, Luster and Tests
- How to Identify Calcite: Hardness, Streak, Luster and Tests
- How to Identify Muscovite (White Mica): Hardness, Streak, Luster and Tests
- How to Identify Biotite (Black Mica): Hardness, Streak, Luster and Tests
- How to Identify Pyrite (Fool's Gold): Hardness, Streak, Luster and Tests
- How to Identify Magnetite: Hardness, Streak, Luster and Tests
- How to Identify Hematite: Hardness, Streak, Luster and Tests
- How to Identify Galena: Hardness, Streak, Luster and Tests
- How to Identify Fluorite: Hardness, Streak, Luster and Tests
- How to Identify Gypsum: Hardness, Streak, Luster and Tests
- How to Identify Talc: Hardness, Streak, Luster and Tests
- How to Identify Halite: Hardness, Streak, Luster and Tests
- How to Identify Garnet: Hardness, Streak, Luster and Tests
- How to Identify Olivine: Hardness, Streak, Luster and Tests
- How to Identify Hornblende (Amphibole): Hardness, Streak, Luster and Tests
Rocks
- How to Identify Obsidian: What to Look For and Home Tests
- How to Identify Chert / Flint: What to Look For and Home Tests
- How to Identify Agate: What to Look For and Home Tests
- How to Identify Petrified Wood: What to Look For and Home Tests
- How to Identify Granite: What to Look For and Home Tests
- How to Identify Basalt: What to Look For and Home Tests
- How to Identify Sandstone: What to Look For and Home Tests
- How to Identify Limestone: What to Look For and Home Tests
- How to Identify Shale: What to Look For and Home Tests
- How to Identify Slate: What to Look For and Home Tests
- How to Identify Marble: What to Look For and Home Tests
- How to Identify Quartzite: What to Look For and Home Tests
Geodes and meteorites
Rock and Mineral Identification Reference
FAQ
Is it real gold or pyrite?
Pyrite is brittle, leaves a greenish-black streak and often shows cube-shaped crystals; gold is soft (2.5–3), dents instead of shattering, and leaves a yellow streak. Open the Pyrite page for the full comparison.
How do I know if a rock is a geode?
Geodes are roughly round, feel lighter than a solid rock of the same size, and often have a bumpy, cauliflower-like outer surface. The Geode page describes where they form and how to open one safely.
Can the app identify a rock from a photo?
It suggests the likely mineral or rock from a clear photo of a fresh surface. Photos cannot measure hardness or streak, so confirm with the tests on each page.