Hydroromarchite is an extremely rare tin-hydroxide mineral that typically forms as a corrosion product on ancient archaeological tin objects submerged in water. It usually appears as microscopic, pearly, white tabular crystals and is frequently associated with the anhydrous mineral romarchite. Due to its formation environment, fine specimens are highly prized by mineral collectors specializing in anthropogenic or rare secondary minerals.
Is this hydroromarchite?
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 hydroromarchite with a known reference. Hydroromarchite 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: encrustations.
Often confused with
Hydroromarchite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside hydroromarchite
Minerals reported to co-occur with hydroromarchite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Sn₃O₂(OH)₂
- Mohs hardness
- 2
- Density
- 4.904 g/cm³
- Colors
- Streak
- White
- Luster
- Adamantine
- Transparency
- Transparent to translucent
- Crystal system
- Tetragonal
- Crystal habit
- Encrustations
- Cleavage
- Three sets visible in SEM images
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Interstitial in quartz-calcite gangue of a massive sphalerite-pyrite ore body (Italy)
Where rockhounds find hydroromarchite
Classic worldwide localities
- Corchia mine, western Emilia Romagna, Italy
- Boundary Falls, Winnipeg River, Ontario, Canada (type locality), where pewter pannikins had been dropped by a voyageur between 1801 and 1821
Field-hunting tip
Where it forms: Interstitial in quartz-calcite gangue of a massive sphalerite-pyrite ore body (Italy). If you start seeing romarchite, siderite, pyrite in float, you are in the right ground. Typical habit: encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hydroromarchite?+
Where is hydroromarchite found?+
Is hydroromarchite safe to handle?+
What rocks look like hydroromarchite?+
What minerals are found with hydroromarchite?+
What kind of rock does hydroromarchite form in?+
What is hydroromarchite used for?+
Find hydroromarchite on the map
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