Derbylite is an uncommon complex oxide mineral usually occurring as tiny, dark, prismatic crystals or needle-like radial aggregates. It is primarily found in iron-rich metamorphic environments where it is often associated with other rare antimony-bearing minerals.
Is this derbylite?
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 derbylite with a known reference. Derbylite sits at Mohs 5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Derbylite leaves a brown streak.
- 3Read the lusterHold the specimen under a strong light. Derbylite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular to prismatic crystals often in radial aggregates.
Often confused with
Derbylite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Derbylite leaves brown, Manaccanite leaves black.
How to tell apart: Streak differs — Derbylite leaves brown, Iron Ore leaves reddish-brown to black; luster reads submetallic on Derbylite and metallic to submetallic on Iron Ore.
Often found alongside derbylite
Minerals reported to co-occur with derbylite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe³⁺₄Ti₃Sb³⁺O₁₃(OH)
- Mohs hardness
- 5
- Density
- 4.4-4.5 g/cm³
- Colors
- Streak
- Brown
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular to Prismatic Crystals Often in Radial Aggregates
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic Rocks, Often Associated with Antimony-bearing Iron Deposits
- Typical price
- $50-500 per specimen
Where rockhounds find derbylite
Classic worldwide localities
- Minas Gerais, Brazil
- Siberia, Russia
- Sweden
Field-hunting tip
Look in metamorphic rocks, often associated with antimony-bearing iron deposits country — that is the host setting where derbylite typically forms. If you start seeing tripuhyite, hematite, quartz in float, you are in the right ground. Field specimens usually show a acicular to prismatic crystals often in radial aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find derbylite on the map
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