Tapiolite-(Mn) is a rare tantalum-bearing mineral that crystallizes in the tetragonal system, distinguishing it from its orthorhombic polymorphs like tantalite. Collectors should look for dark, blocky, or dipyramidal crystals typically found within highly fractionated rare-element granitic pegmatites. Due to its high density and submetallic luster, it is often identified by its characteristic heavy weight relative to size.
Is this tapiolite-(mn)?
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 tapiolite-(mn) with a known reference. Tapiolite-(Mn) sits at Mohs 6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: dark brown.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic.
- 4Match the color rangeCompare against the expected color range: dark brown, black brown.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: massive.
Often confused with
Tapiolite-(Mn) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Tapiolite-(Mn) leaves dark brown, Columbite leaves blackish brown.
How to tell apart: Streak differs, so Tapiolite-(Mn) leaves dark brown, Tapiolite-(Fe) leaves brown; luster reads submetallic on Tapiolite-(Mn) and metallic on Tapiolite-(Fe).
How to tell apart: Streak differs, so Tapiolite-(Mn) leaves dark brown, Tantalite leaves black to reddish-brown.
Often found alongside tapiolite-(mn)
Minerals reported to co-occur with tapiolite-(mn). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MnTa₂O₆
- Mohs hardness
- 6
- Density
- 7.72 g/cm³
- Colors
- Streak
- Dark brown
- Luster
- Submetallic
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Ore of tantalum
- Host rock
- Accessory mineral in a lithium-rich pegmatite dike
Where rockhounds find tapiolite-(mn)
Classic worldwide localities
- Viitaniemi pegmatite, Erajarvi area, Orivesi, Finland (type locality)
Field-hunting tip
Where it forms: Accessory mineral in a lithium-rich pegmatite dike. If you start seeing microcline, albite, quartz in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tapiolite-(mn)?+
Where is tapiolite-(mn) found?+
What rocks look like tapiolite-(mn)?+
What minerals are found with tapiolite-(mn)?+
What kind of rock does tapiolite-(mn) form in?+
What is tapiolite-(mn) used for?+
Find tapiolite-(mn) on the map
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