Calciosamarskite is a rare niobium-tantalum-rich mineral within the samarskite group characterized by its high calcium content. It typically occurs as black, massive, radioactive grains in complex granite pegmatites and is often identified via X-ray diffraction due to its metamict state.
Is this calciosamarskite?
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 calciosamarskite with a known reference. Calciosamarskite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Calciosamarskite leaves a dark brown streak.
- 3Read the lusterHold the specimen under a strong light. Calciosamarskite 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: massive, anhedral grains.
Often confused with
Calciosamarskite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside calciosamarskite
Minerals reported to co-occur with calciosamarskite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Fe,Y,U)₂(Nb,Ta,Ti)₂O₈
- Mohs hardness
- 5-6
- Density
- 5.6-5.8 g/cm³
- Colors
- Streak
- Dark Brown
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Massive, Anhedral Grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $50-300 per specimen depending on size and provenance
Where rockhounds find calciosamarskite
Classic worldwide localities
- Northwest Territories, Canada
- Madagascar
- Norway
Field-hunting tip
Look in granite pegmatites country — that is the host setting where calciosamarskite typically forms. If you start seeing albite, microcline, beryl in float, you are in the right ground. Field specimens usually show a massive, anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify calciosamarskite?+
Where is calciosamarskite found?+
How much is calciosamarskite worth?+
Is calciosamarskite safe to handle?+
What rocks look like calciosamarskite?+
What minerals are found with calciosamarskite?+
What kind of rock does calciosamarskite form in?+
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Find calciosamarskite on the map
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