Ramsdellite is a manganese oxide mineral typically found as metallic, black prismatic to needle-like crystals or massive, fibrous aggregates. It is often confused with pyrolusite, though it is usually distinguished by its orthorhombic structure and distinct cleavage. Collectors primarily seek out well-defined bladed crystals from famous historical manganese localities.
Is this ramsdellite?
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 ramsdellite with a known reference. Ramsdellite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ramsdellite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Ramsdellite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: black, gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals, massive, fibrous, platy.
Often confused with
Ramsdellite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Pyrolusite is the harder of the two (Mohs 6-6.5 vs. 3).
How to tell apart: Nsutite is the harder of the two (Mohs 6-6.5 vs. 3); streak differs — Ramsdellite leaves black, Nsutite leaves dark brown; luster reads metallic on Ramsdellite and submetallic on Nsutite.
How to tell apart: Manganite is the harder of the two (Mohs 4 vs. 3); streak differs — Ramsdellite leaves black, Manganite leaves dark reddish-brown; luster reads metallic on Ramsdellite and submetallic on Manganite.
Often found alongside ramsdellite
Minerals reported to co-occur with ramsdellite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MnO₂
- Mohs hardness
- 3
- Density
- 4.8 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic Crystals, Massive, Fibrous, Platy
- Cleavage
- Perfect in One Direction
- Rarity
- Uncommon
- Uses
- Collector, Ore of Manganese
- Host rock
- Sedimentary Manganese Deposits, Hydrothermal Veins
- Typical price
- $10-60 per specimen depending on crystal definition
Where rockhounds find ramsdellite
Classic worldwide localities
- Lake Valley, New Mexico, USA
- Sitapar, India
- Tanzanite, Tanzania
- Postmasburg, South Africa
Field-hunting tip
Look in sedimentary manganese deposits, hydrothermal veins country — that is the host setting where ramsdellite typically forms. If you start seeing pyrolusite, lithiophorite, goethite in float, you are in the right ground. Field specimens usually show a prismatic crystals, massive, fibrous, platy habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find ramsdellite on the map
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