Romarchite is a rare tin oxide mineral typically found in the oxidation zones of tin deposits. It is often identified by its distinct black to dark-brown platy crystals and high density resulting from its tin content. Collectors primarily seek it as an uncommon mineral species associated with historical mining artifacts or oxidized hydrothermal veins.
Is this romarchite?
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 romarchite with a known reference. Romarchite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Romarchite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Romarchite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, dark brown, reddish-brown.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: platy crystals, granular aggregates.
Often confused with
Romarchite 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); streak differs — Romarchite leaves black, Cassiterite leaves white; luster reads submetallic on Romarchite and adamantine on Cassiterite.
How to tell apart: Streak differs — Romarchite leaves black, Hydroromarchite leaves white; luster reads submetallic on Romarchite and pearly on Hydroromarchite.
Often found alongside romarchite
Minerals reported to co-occur with romarchite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SnO
- Mohs hardness
- 2
- Density
- 9.18 g/cm³
- Streak
- Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Platy Crystals, Granular Aggregates
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector, Scientific
- Host rock
- Oxidized Tin-bearing Hydrothermal Deposits
- Typical price
- $50-500 thumbnail specimens
Where rockhounds find romarchite
Classic worldwide localities
- Cornwall, England
- Cassandra mine, Greece
- Broken Hill, Australia
Field-hunting tip
Look in oxidized tin-bearing hydrothermal deposits country — that is the host setting where romarchite typically forms. If you start seeing hydroromarchite, cassiterite, stannite in float, you are in the right ground. Field specimens usually show a platy crystals, granular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find romarchite on the map
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