Leucosphenite is a rare barium-titanium silicate known for its distinct wedge-shaped tabular crystals and strong blue fluorescence under short-wave UV light. It is most famous among collectors for specimens sourced from the alkaline igneous complexes of Mont Saint-Hilaire. Due to its rarity and specific geological occurrence, it is primarily sought by advanced mineral collectors and those interested in exotic pegmatite minerals.
Is this leucosphenite?
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 leucosphenite with a known reference. Leucosphenite sits at Mohs 6-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to pearly.
- 4Match the color rangeCompare against the expected color range: colorless, lemon yellow, brown, pale blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: pseudo hexagonal, striated, wedge shaped.
Often confused with
Leucosphenite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside leucosphenite
Minerals reported to co-occur with leucosphenite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₄BaTi₂B₂Si₁₀O₃₀
- Mohs hardness
- 6-6.5
- Density
- 3.04-3.09 g/cm³
- Streak
- White
- Luster
- Vitreous to pearly
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Pseudo hexagonal, striated, wedge shaped
- Cleavage
- {010}, {001}, distinct
- Fluorescence
- Yellowish white under SW UV
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In pegmatite in syenite (Greenland, Russia, Canada); in aegirine-feldspar veins (Inagli massif, Russia); an authigenic mineral in shales (Utah and Wyoming, USA)
Where rockhounds find leucosphenite
Classic worldwide localities
- Green River Formation, in the Uinta basin, Utah and in the Bridger basin, Sweetwater Co., Wyoming, USA
- Narssârssuk, Greenland
- Mont Saint-Hilaire, Quebec, Canada
- Inagli massif, 30 km west of Aldan, Yakutia, and in the Lovozero massif, Kola Peninsula, Russia
- Dara-i-Pioz massif, Alai Range, Tien Shan, Tajikistan
- Ohmi, Niigata Prefecture, Japan
Field-hunting tip
Where it forms: In pegmatite in syenite (Greenland, Russia, Canada); in aegirine-feldspar veins (Inagli massif, Russia); an authigenic mineral in shales (Utah and Wyoming, USA). If you start seeing elpidite, aegirine, epididymite in float, you are in the right ground. Typical habit: pseudo hexagonal, striated, wedge shaped. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify leucosphenite?+
Where is leucosphenite found?+
What rocks look like leucosphenite?+
What minerals are found with leucosphenite?+
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What is leucosphenite used for?+
Find leucosphenite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
