Foordite is a rare tin-niobium oxide belonging to the tapiolite group. It is primarily found in granitic pegmatite environments and is visually difficult to distinguish from other dark, opaque oxide minerals without chemical analysis. Collectors typically seek it for its rarity and its specific association with pegmatite mineral suites.
Is this foordite?
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 foordite with a known reference. Foordite 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: yellowish white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to adamantine.
- 4Match the color rangeCompare against the expected color range: brownish yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic to tabular crystals.
Often confused with
Foordite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Foordite leaves yellowish white, Columbite leaves blackish brown; luster reads vitreous to adamantine on Foordite and submetallic on Columbite.
How to tell apart: Streak differs, so Foordite leaves yellowish white, Cassiterite leaves white, pale brown, pale gray; luster reads vitreous to adamantine on Foordite and adamantine to adamantine metallic, splendent; may be greasy on fractures on Cassiterite.
Often found alongside foordite
Minerals reported to co-occur with foordite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SnNb₂O₆
- Mohs hardness
- 6
- Density
- 6.734 g/cm³
- Colors
- Streak
- Yellowish white
- Luster
- Vitreous to adamantine
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic to tabular crystals
- Cleavage
- {100}, perfect; {011}, poor
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- A very rare mineral, in an alluvial pebble originating from a highly differentiated granite pegmatite, formed under reducing conditions deficient in Fe, Mn, Na, Ca, and F (Lutsiro, Rwanda)
Where rockhounds find foordite
Classic worldwide localities
- Kubitaka, near Punia, Kivu Province, Congo (Zaire)
Field-hunting tip
Where it forms: A very rare mineral, in an alluvial pebble originating from a highly differentiated granite pegmatite, formed under reducing conditions deficient in Fe, Mn, Na, Ca, and F (Lutsiro, Rwanda). If you start seeing ferrocolumbite, cassiterite, stannoan plumbomicrolite in float, you are in the right ground. Typical habit: prismatic to tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify foordite?+
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What rocks look like foordite?+
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Find foordite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
