Bismutotantalite is a very rare bismuth tantalate mineral found primarily in complex granitic pegmatites. It is sought after by mineral collectors for its high density and characteristic prismatic crystal habits, which are often found associated with other rare earth minerals.
Is this bismutotantalite?
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 bismutotantalite with a known reference. Bismutotantalite sits at Mohs 5-5.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellow, yellow-brown to black.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine to submetallic.
- 4Match the color rangeCompare against the expected color range: light brown, black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: euhedral crystals, prismatic.
Often confused with
Bismutotantalite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Bismutotantalite leaves yellow, yellow-brown to black, Tantalite leaves black to reddish-brown; luster reads adamantine to submetallic on Bismutotantalite and submetallic to resinous on Tantalite.
How to tell apart: Streak differs, so Bismutotantalite leaves yellow, yellow-brown to black, Stibiotantalite leaves pale yellow to yellow-brown; luster reads adamantine to submetallic on Bismutotantalite and resinous to adamantine on Stibiotantalite.
Often found alongside bismutotantalite
Minerals reported to co-occur with bismutotantalite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BiTaO₄
- Mohs hardness
- 5-5.5
- Density
- 8.15-8.89 g/cm³
- Colors
- Streak
- Yellow, yellow-brown to black
- Luster
- Adamantine to submetallic
- Transparency
- Opaque, transparent in very thin fragments
- Crystal system
- Orthorhombic
- Crystal habit
- Euhedral crystals, prismatic
- Cleavage
- Partings or cleavages on {010}, good; {101}, {100}, distinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In granite pegmatite (Uganda and Mozambique); as stream-rounded pebbles (Acari, Brazil)
Where rockhounds find bismutotantalite
Classic worldwide localities
- Gamba Hill, near Kambala, southwest Uganda
- Muiâne pegmatite, Alto Ligonha district, Mozambique
- Analamisakana, Madagascar
- Rio Grande do Norte, from Acari, near Picuí, Campina Grande, at Carnauba dos Dantas, Saco do Onca, at Parelhas, near Recife, and at Currais Novos, Brazil
- Baldino mine, Junco, Paraíba, Brazil
- Nagatareyama, Fukuoka Prefecture, Japan
Field-hunting tip
Where it forms: In granite pegmatite (Uganda and Mozambique); as stream-rounded pebbles (Acari, Brazil). If you start seeing muscovite, schorl, cassiterite in float, you are in the right ground. Typical habit: euhedral crystals, prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify bismutotantalite?+
Where is bismutotantalite found?+
Is bismutotantalite safe to handle?+
What rocks look like bismutotantalite?+
What minerals are found with bismutotantalite?+
What kind of rock does bismutotantalite form in?+
What is bismutotantalite used for?+
Find bismutotantalite on the map
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