Stibiotantalite is a rare antimony-tantalum oxide typically found in complex granite pegmatites. It is sought after by collectors for its high refractive index and adamantine luster, often appearing as wedge-shaped or flattened prismatic crystals.
Is this stibiotantalite?
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 stibiotantalite with a known reference. Stibiotantalite sits at Mohs 5.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale yellow to yellow-brown.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous to adamantine.
- 4Match the color rangeCompare against the expected color range: yellow, brown, greenish yellow, light yellow brown, dark brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic, tabular, or massive.
Often confused with
Stibiotantalite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Stibiotantalite leaves pale yellow to yellow-brown, Cassiterite leaves white, pale brown, pale gray; luster reads resinous to adamantine on Stibiotantalite and adamantine to adamantine metallic, splendent; may be greasy on fractures on Cassiterite.
How to tell apart: Streak differs, so Stibiotantalite leaves pale yellow to yellow-brown, Tantalite leaves black to reddish-brown; luster reads resinous to adamantine on Stibiotantalite and submetallic to resinous on Tantalite.
How to tell apart: Streak differs, so Stibiotantalite leaves pale yellow to yellow-brown, Scheelite leaves white; luster reads resinous to adamantine on Stibiotantalite and vitreous to adamantine on Scheelite.
Often found alongside stibiotantalite
Minerals reported to co-occur with stibiotantalite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SbTaO₄
- Mohs hardness
- 5.5
- Density
- 7.53 g/cm³
- Colors
- Streak
- Pale yellow to yellow-brown
- Luster
- Resinous to adamantine
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic, tabular, or massive
- Cleavage
- {001}, distinct; {100} indistinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An uncommon accessory mineral in complex granite pegmatites
Where rockhounds find stibiotantalite
Classic worldwide localities
- Topsham, Sagadahoc Co., Maine, USA
- San Diego Co., Himalaya mine, Mesa Grande district, California, USA
- Katerina, Stewart, and Vandenburg mines, Pala district, California, USA
- Little Three mine, Ramona district, California, USA
- Greenbushes tin placers, Wodgina district, Western Australia
- Muiâne and other mines, Alto Ligonha, Mozambique
Field-hunting tip
Where it forms: An uncommon accessory mineral in complex granite pegmatites. If you start seeing tantalite, antimony, allemontite in float, you are in the right ground. Typical habit: prismatic, tabular, or massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify stibiotantalite?+
Where is stibiotantalite found?+
Is stibiotantalite safe to handle?+
What rocks look like stibiotantalite?+
What minerals are found with stibiotantalite?+
What kind of rock does stibiotantalite form in?+
What is stibiotantalite used for?+
Find stibiotantalite on the map
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