Heftetjernite is a rare scandium tantalum oxide, typically dark brown to greenish brown. It occurs in vugs in albite in a mixed LCT-NYF type cleavelandite-amazonite pegmatite. It was first described from Heftetjern pegmatite, between Høydalen and Skarsfjell, Tørdal, Telemark, Norway.
Is this heftetjernite?
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 heftetjernite with a known reference. Heftetjernite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Heftetjernite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Heftetjernite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: dark brown, greenish brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: elongate tabular to columnar crystals.
Often confused with
Heftetjernite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Danalite is the harder of the two (Mohs 5.5-6 vs. 4.5); luster reads adamantine on Heftetjernite and vitreous on Danalite.
How to tell apart: Genthelvite is the harder of the two (Mohs 6-6.5 vs. 4.5); luster reads adamantine on Heftetjernite and vitreous on Genthelvite.
Often found alongside heftetjernite
Minerals reported to co-occur with heftetjernite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- ScTaO₄
- Mohs hardness
- 4.5
- Density
- 6.44 g/cm³
- Colors
- Streak
- White
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Elongate Tabular to Columnar Crystals
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Nepheline Syenite Pegmatites
Where rockhounds find heftetjernite
Classic worldwide localities
- Heftetjern, Norway
- Kola Peninsula, Russia
Field-hunting tip
Look in nepheline syenite pegmatites country, the host setting where heftetjernite typically forms. If you start seeing microcline, quartz, zircon in float, you are in the right ground. Field specimens usually show a elongate tabular to columnar crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify heftetjernite?+
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Find heftetjernite on the map
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