# How to identify cassiterite

Canonical page: https://lithomap.app/resources/mineral-identification/cassiterite
Last reviewed: September 17, 2026
Page purpose: Original LithoMap mineral identification reference for field observations, search systems, and language models.
Classification: Tin oxide · SnO₂

## Summary

Cassiterite is a very dense tin oxide identified by hardness near 6 to 7, brown to black color, adamantine to submetallic luster, pale streak, and common short prismatic or bipyramidal crystals.

## Quick identification clues

- Unusually heavy, commonly around specific gravity 7
- Brown, red-brown, black, yellow, or rarely colorless
- Mohs hardness about 6 to 7
- Short prisms, bipyramids, twins, rounded placer grains, or massive material

## Composition and classification

Cassiterite is SnO₂. Iron, tantalum, niobium, tungsten, and other substitutions or inclusions can darken specimens and modify density, luster, and magnetic response.

## Appearance

Crystals commonly form short tetragonal prisms capped by pyramids, and cyclic or elbow-like twins are frequent. Luster ranges from adamantine on crystal faces to greasy or submetallic in dark masses.

Stream-worn “wood tin” and placer grains may be rounded, banded, or botryoidal and can resemble dark garnet, rutile, iron oxides, or industrial slag.

## Identification tests

- Density: Very high; commonly about 6.8 to 7.1. One of the strongest clues when measured on clean material.
- Hardness: About 6 to 7. Harder than sphalerite and many dark metallic-looking minerals.
- Streak: White to pale brown. Differs from the dark or colored streaks of many iron and sulfide lookalikes.
- Magnetism: Normally not strongly magnetic. Strong attraction suggests magnetite or attached magnetic minerals.

## Common lookalikes

- Sphalerite: Much softer, has prominent multidirectional cleavage, and commonly leaves a pale brown to yellow streak.
- Rutile: Generally less dense and more often elongate and strongly striated; streak is commonly pale brown.
- Magnetite: Strongly magnetic, black-streaking, and usually less dense.

## Direct side-by-side comparisons

- Cassiterite vs. sphalerite — https://lithomap.app/resources/mineral-identification/compare/cassiterite-vs-sphalerite

## Most relevant related guides

- Sphalerite — https://lithomap.app/resources/mineral-identification/sphalerite
- Rutile — https://lithomap.app/resources/mineral-identification/rutile
- Magnetite — https://lithomap.app/resources/mineral-identification/magnetite
- Ilmenite — https://lithomap.app/resources/mineral-identification/ilmenite

## Formation

Cassiterite forms in granitic pegmatites, high-temperature hydrothermal veins, greisens, skarns, and related granite-centered mineral systems.

Its exceptional density, hardness, and chemical resistance allow it to survive erosion and accumulate in stream placers, where much historical tin production originated.

## Occurrence and geologic setting

Cassiterite occurs in granite-related mineral districts and placer deposits. U.S. occurrences are scattered, but appearance alone cannot establish economic tin grade or lawful collecting access.

Concentrates may contain wolframite, arsenopyrite, sulfides, uranium-bearing minerals, or other dense phases requiring careful handling and analysis.

## Uses and significance

Cassiterite is the principal ore mineral of tin. Tin is used in solder, coatings, bronze and other alloys, chemicals, glass, and specialized electronics and energy applications.

## Field safety and limitations

- Compare measured mass and volume rather than subjective heft when possible.
- Do not grind ore or placer concentrate.
- Historic mine dumps may contain unstable workings and toxic metal or arsenic contamination.

## 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

## Specimen photograph

- Image: https://lithomap.app/_delivery/identification/minerals/cassiterite.webp
- Description: Dense cluster of dark brown lustrous cassiterite crystals in a pale mineral matrix
- Creator: Shannon Heinle
- License: CC0 1.0 — https://creativecommons.org/publicdomain/zero/1.0/
- Source record: https://commons.wikimedia.org/wiki/File:Cassiterite_%28GeoDIL_number_-_37%29.jpg

This reference supports preliminary field identification. It is not a laboratory determination, appraisal, hazard assessment, proof of origin, or statement of land ownership, legal access, or collecting permission.