Field-first decision support

Rock and mineral identification tool

Turn several observable clues into a short list of possible guide matches. This tool explains its logic and keeps uncertainty visible.

Download LithoMapPut U.S. geology in your pocket.Choose Google Play or the App Store.

Interactive field helper

Match several observations

Choose the closest material type, then select only clues you can confirm on a fresh surface. The tool checks every current LithoMap identification guide and explains why each candidate appears.

0 clues selectedAdd at least two independent clues for a more useful shortlist.

Material type

Texture and structure

Composition and tests

Select two or more clues when possible

Color alone is usually too variable. Texture, breakage, hardness, streak, magnetism, density, and a controlled acid response usually carry more information.

Important: These are candidates to investigate, not an identification. The ranking is a transparent clue match, not image recognition, appraisal, or laboratory analysis.

Start gently

Observe before testing

Begin with a clean, unpolished surface. Note whether grains interlock, are cemented, or align in a fabric. For minerals, examine luster, crystal shape, and breakage before making a streak or hardness mark.

Converging evidence

Why several clues matter

Many unrelated materials share a color. Weathering also changes surfaces, and rocks contain mixtures of minerals. Two or three independent observations are more useful than one dramatic-looking property.

See step-by-step field-test procedures.

Prefer to browse? Open the complete rock guide directory or mineral guide directory.

Safety

Tests to avoid or control

Do not taste minerals. Avoid creating dust, striking unknown fibrous or radioactive material, or applying acid to finished stone, fossils, artifacts, monuments, or protected outcrops. Use eye protection and the least destructive method available.

Scientific limit

When a hand sample is not enough

Fine-grained, altered, weathered, mixed, or manufactured samples may require thin-section microscopy, chemistry, X-ray diffraction, or expert examination. A possible match does not establish value, origin, ownership, or collecting permission.