Joosteite is a rare phosphate mineral typically found as an alteration product within granite pegmatites. It usually occurs in massive or granular habits associated with other triphylite group members in the Jooste pegmatite of Namibia.
Is this joosteite?
4-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 joosteite with a known reference. Joosteite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
- 2Read the lusterHold the specimen under a strong light. Luster: metallic.
- 3Match the color rangeCompare against the expected color range: black.
- 4Look at form & habitCrystal system: monoclinic. Typical habit: massive, granular.
Often confused with
Joosteite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside joosteite
Minerals reported to co-occur with joosteite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn²⁺Mn³⁺(PO₄)O
- Mohs hardness
- 4
- Density
- 4.13 g/cm³
- Colors
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Massive, granular
- Cleavage
- Distinct on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- From the alteration of oxidized sicklerite in a granitic rare-element pegmatite
Where rockhounds find joosteite
Classic worldwide localities
- Helikon II pegmatite, Karibib, Namibia
Field-hunting tip
Where it forms: From the alteration of oxidized sicklerite in a granitic rare-element pegmatite. If you start seeing lithiophilite, sicklerite, eosphorite in float, you are in the right ground. Typical habit: massive, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify joosteite?+
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What rocks look like joosteite?+
What minerals are found with joosteite?+
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Find joosteite on the map
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