LithoMap

Mineral identification comparison

Cassiterite vs. sphalerite: how to tell them apart

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.

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Dense cluster of dark brown lustrous cassiterite crystals in a pale mineral matrix
CassiteriteTin oxide · SnO₂Photo: Shannon Heinle · CC0 1.0
Dark resinous sphalerite specimen from Creede, Colorado
SphaleriteZinc sulfide · ZnSPhoto: U.S. Geological Survey · Public domain
Quick answer

The most useful distinction

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

Cassiterite and Sphalerite comparison table

PropertyCassiteriteSphaleriteHow to use it
HardnessMohs about 6 to 7Mohs about 3.5 to 4Cassiterite can scratch glass; sphalerite is readily scratched by steel.
DensityVery high, commonly about 6.8 to 7.1High, commonly about 3.9 to 4.1Cassiterite is dramatically denser at equal volume.
CleavagePoor or indistinctPerfect in six directionsRepeated bright cleavage surfaces favor sphalerite.
StreakWhite to pale brownWhite, pale yellow, or brownStreak can overlap and is secondary to hardness, density, and cleavage.
Field sequence

A practical identification sequence

  1. 1

    Inspect existing breaks for repeated cleavage faces.

  2. 2

    Test hardness only on a small expendable edge.

  3. 3

    Compare equal-volume pieces or measure specific gravity.

  4. 4

    Use chemistry or diffraction if the sample is fine-grained or mixed with sulfides.

Limits and cautions

Where the distinction gets difficult

  • 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.

Use several independent observations. This comparison supports preliminary field identification, not laboratory confirmation, appraisal, proof of origin, or collecting permission.

Common questions

Cassiterite vs. sphalerite FAQ

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.

Source basis

Authoritative sources

LithoMap wrote this comparison in original language from the physical properties and geological concepts supported by these public scientific references.

Editorial review: September 17, 2026.

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