Rock Identifier
A rock is a mixture of minerals, so you identify it by grain and texture, not a single hardness. Note what you can see and Gemdle ranks the possible rocks it matches. (Because rocks are aggregates, the Mohs filter matters less here than texture and how the grains fit together.) Searches 48 rocks.
How to identify a rock step by step
- Grain size & texture — can you see individual mineral grains, or is it fine and smooth? Glassy (obsidian), frothy (pumice) or gritty (sandstone)?
- How the grains fit — interlocking crystals (igneous, e.g. granite), layers or rounded grains (sedimentary), or banded/foliated (metamorphic, e.g. gneiss)?
- Overall colour — light rocks tend to be quartz/feldspar-rich; dark rocks iron/magnesium-rich.
- Hardness of the grains — do they scratch glass, or crumble?
- Fizz test — a drop of vinegar fizzes on limestone and marble (carbonate rocks).
Popular rocks to compare against
Frequently asked questions
How do I identify a rock vs a mineral?
A mineral is a single substance with one composition and crystal structure; a rock is an aggregate of one or more minerals. If you can see different grains or crystals mixed together, it is a rock — use this page. For a single uniform crystal, try the mineral identifier.
Can you identify a rock from a photo alone?
Not reliably. Geologists examine a specimen from several angles and test hardness, streak and density. A photo gets you a shortlist; Gemdle's identifier uses the same observable clues to rank possibilities you then confirm in person.