Demicheleite-(Br) is an extremely rare bismuth sulfobromide found primarily in volcanic fumaroles. It typically appears as distinct, bright orange-red tabular crystals often associated with volcanic sulfur deposits.
Is this demicheleite-(br)?
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 demicheleite-(br) with a known reference. Demicheleite-(Br) sits at Mohs 1.5-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: red.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic.
- 4Match the color rangeCompare against the expected color range: dark red, black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: euhedral crystals, microscopic crystals, prismatic.
Often confused with
Demicheleite-(Br) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Demicheleite-(Br) leaves red, Demicheleite-(Cl) leaves brown.
How to tell apart: Streak differs, so Demicheleite-(Br) leaves red, Bismutite leaves gray; luster reads submetallic on Demicheleite-(Br) and vitreous, waxy, may be dull to earthy on Bismutite.
How to tell apart: Streak differs, so Demicheleite-(Br) leaves red, Bismuthinite leaves lead-gray; luster reads submetallic on Demicheleite-(Br) and metallic on Bismuthinite.
Often found alongside demicheleite-(br)
Minerals reported to co-occur with demicheleite-(br). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BiSBr
- Mohs hardness
- 1.5-2
- Density
- 6.312 g/cm³
- Streak
- Red
- Luster
- Submetallic
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Euhedral crystals, microscopic crystals, prismatic
- Cleavage
- None observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A product of fumarolic alteration of pyroclastic breccia
Where rockhounds find demicheleite-(br)
Classic worldwide localities
- La Fossa crater, Vulcano Island, Aeolian archipelago, Sicily, Italy
Field-hunting tip
Where it forms: A product of fumarolic alteration of pyroclastic breccia. If you start seeing demicheleite-, pseudocotunnite, bismoclite in float, you are in the right ground. Typical habit: euhedral crystals, microscopic crystals, prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify demicheleite-(br)?+
Where is demicheleite-(br) found?+
Is demicheleite-(br) safe to handle?+
What rocks look like demicheleite-(br)?+
What minerals are found with demicheleite-(br)?+
What kind of rock does demicheleite-(br) form in?+
What is demicheleite-(br) used for?+
Find demicheleite-(br) on the map
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