Rynersonite is an extremely rare tantalum mineral that typically occurs as small, resinous tabular crystals. It is primarily found within complex granite pegmatites and is often associated with other rare earth minerals.
Is this rynersonite?
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 rynersonite with a known reference. Rynersonite sits at Mohs 4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Rynersonite leaves a yellowish white streak.
- 3Read the lusterHold the specimen under a strong light. Rynersonite typically shows a resinous luster.
- 4Match the color rangeCompare against the expected color range: yellow, brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals.
Often confused with
Rynersonite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Euxenite-(Y) is the harder of the two (Mohs 5.5-6.5 vs. 4); streak differs — Rynersonite leaves yellowish white, Euxenite-(Y) leaves yellowish-brown; luster reads resinous on Rynersonite and submetallic on Euxenite-(Y).
How to tell apart: Samarskite-(Y) is the harder of the two (Mohs 5-6 vs. 4); streak differs — Rynersonite leaves yellowish white, Samarskite-(Y) leaves dark brown; luster reads resinous on Rynersonite and submetallic on Samarskite-(Y).
Often found alongside rynersonite
Minerals reported to co-occur with rynersonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaTa₂O₆
- Mohs hardness
- 4
- Density
- 5.68 g/cm³
- Streak
- Yellowish White
- Luster
- Resinous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $50-300 per specimen
Where rockhounds find rynersonite
Classic worldwide localities
- Mesa Grande, California, USA
Field-hunting tip
Look in granite pegmatites country — that is the host setting where rynersonite typically forms. If you start seeing beryl, quartz, microcline in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find rynersonite on the map
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