Barwoodite is a rare manganese niobium silicate, typically brownish red. It occurs in miarolitic cavities in pegmatite in a nepheline syenite pluton. It was first described from Big Rock quarry, Granite Mountain, Little Rock, Pulaski County, Arkansas, USA.
Is this barwoodite?
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 barwoodite with a known reference. Barwoodite sits at Mohs ~3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light orange.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: brownish red.
- 5Look at form & habitCrystal system: trigonal. Typical habit: prismatic crystals.
Often confused with
Barwoodite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Arfvedsonite is the harder of the two (Mohs 5-6 vs. ~3.5); streak differs, so Barwoodite leaves light orange, Arfvedsonite leaves deep bluish gray, gray-green.
How to tell apart: Streak differs, so Barwoodite leaves light orange, Astrophyllite leaves golden; luster reads vitreous on Barwoodite and submetallic, pearly, greasy on Astrophyllite.
Often found alongside barwoodite
Minerals reported to co-occur with barwoodite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn²⁺₆(Nb⁵⁺,☐)₂(SiO₄)₂(O,OH)₆
- Mohs hardness
- ~3.5
- Density
- 4.168 g/cm³
- Colors
- Streak
- Light orange
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Prismatic crystals
- Cleavage
- Perfect on {00*1}
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In miarolitic cavities in pegmatite in a nepheline syenite pluton
Where rockhounds find barwoodite
Classic worldwide localities
- Big Rock quarry (also known as the 3M quarry), Granite Mountain, Little Rock, Pulaski County, Arkansas, USA
Field-hunting tip
Where it forms: In miarolitic cavities in pegmatite in a nepheline syenite pluton. If you start seeing aegirine, albite, analcime in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find barwoodite on the map
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