Varlamoffite is a secondary tin mineral typically occurring as a yellow oxidation product of stannite or cassiterite. It is most commonly found as earthy, powdery masses or thin crusts lining cavities in weathered tin-bearing hydrothermal veins.
Is this varlamoffite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch varlamoffite with a known reference. Varlamoffite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Varlamoffite leaves a yellowish streak.
- 3Read the lusterHold the specimen under a strong light. Varlamoffite typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-brown, pale yellow.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: powdery, earthy masses, coatings.
Often confused with
Varlamoffite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Cassiterite is the harder of the two (Mohs 6-7 vs. 2-3); streak differs — Varlamoffite leaves yellowish, Cassiterite leaves white; luster reads dull on Varlamoffite and adamantine on Cassiterite.
How to tell apart: Limonite is the harder of the two (Mohs 4-5.5 vs. 2-3); streak differs — Varlamoffite leaves yellowish, Limonite leaves yellowish-brown; luster reads dull on Varlamoffite and submetallic to earthy on Limonite.
Often found alongside varlamoffite
Minerals reported to co-occur with varlamoffite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Sn,Fe)(O,OH)₂
- Mohs hardness
- 2-3
- Density
- 4.0-5.0 g/cm³
- Streak
- Yellowish
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Powdery, Earthy Masses, Coatings
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Tin Ore Deposits
- Typical price
- $20-100 per specimen
Where rockhounds find varlamoffite
Classic worldwide localities
- Republic of the Congo
- Cornwall, UK
- Bolivia
- Russia
Field-hunting tip
Look in oxidized tin ore deposits country — that is the host setting where varlamoffite typically forms. If you start seeing cassiterite, stannite, goethite in float, you are in the right ground. Field specimens usually show a powdery, earthy masses, coatings habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find varlamoffite on the map
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