# Cassiterite vs. sphalerite: how to tell them apart

Canonical page: https://lithomap.app/resources/mineral-identification/compare/cassiterite-vs-sphalerite
Last reviewed: September 17, 2026
Page purpose: Original LithoMap side-by-side field identification reference for search systems and language models.

## Summary

Cassiterite and dark sphalerite can both be brown to black with high luster and notable density. Cassiterite is much harder and denser; sphalerite has excellent cleavage, lower hardness, and commonly a pale yellow to brown streak.

## Bottom line

Use existing breakage and hardness on expendable material. Very heavy, hard material with poor cleavage favors cassiterite; softer resinous material with repeated cleavage favors sphalerite.

## Side-by-side evidence

- Hardness: Cassiterite — Mohs about 6 to 7 Sphalerite — Mohs about 3.5 to 4 Interpretation — Cassiterite can scratch glass; sphalerite is readily scratched by steel.
- Density: Cassiterite — Very high, commonly about 6.8 to 7.1 Sphalerite — High, commonly about 3.9 to 4.1 Interpretation — Cassiterite is dramatically denser at equal volume.
- Cleavage: Cassiterite — Poor or indistinct Sphalerite — Perfect in six directions Interpretation — Repeated bright cleavage surfaces favor sphalerite.
- Streak: Cassiterite — White to pale brown Sphalerite — White, pale yellow, or brown Interpretation — Streak can overlap and is secondary to hardness, density, and cleavage.

## Field sequence

1. Inspect existing breaks for repeated cleavage faces.
2. Test hardness only on a small expendable edge.
3. Compare equal-volume pieces or measure specific gravity.
4. Use chemistry or diffraction if the sample is fine-grained or mixed with sulfides.

## Limits and cautions

- Dark iron-rich sphalerite can look metallic and feel denser than expected.
- Cassiterite concentrates may contain arsenic- or sulfide-bearing minerals.
- Avoid grinding, heating, or acid-testing unknown ore.

## Frequently asked questions

### Which mineral is heavier?

Cassiterite is usually far denser than sphalerite at equal volume.

### Can cassiterite be transparent?

Thin edges and uncommon light-colored crystals can be translucent or transparent, although most ore specimens are dark.

### Does sphalerite scratch glass?

Typical sphalerite is too soft to scratch ordinary glass reliably; fresh cassiterite commonly can.

## Related identification guides

- Cassiterite: https://lithomap.app/resources/mineral-identification/cassiterite
- Sphalerite: https://lithomap.app/resources/mineral-identification/sphalerite

## Authoritative sources

- Tin Statistics and Information — U.S. Geological Survey: https://www.usgs.gov/centers/national-minerals-information-center/tin-statistics-and-information
- Minerals and their physical properties — U.S. National Park Service: https://www.nps.gov/subjects/geology/minerals.htm
- Mohs Hardness Scale — U.S. National Park Service: https://www.nps.gov/articles/mohs-hardness-scale.htm
- Natural Gemstones: Mineral Gemstones — U.S. Geological Survey: https://pubs.usgs.gov/gip/gemstones/mineral.html
- Zinc Statistics and Information — U.S. Geological Survey: https://www.usgs.gov/centers/national-minerals-information-center/zinc-statistics-and-information

This reference supports preliminary field identification. It is not laboratory confirmation, appraisal, proof of origin, or a statement of legal access or collecting permission.