Lamprophyllite is a striking silicate mineral typically found as bladed or acicular crystals with a bright, vitreous luster. It is highly sought after by collectors for its beautiful radiating sprays which often contrast sharply against dark igneous matrix rocks like nepheline syenite.
Is this lamprophyllite?
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 lamprophyllite with a known reference. Lamprophyllite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale yellow, may have an orange tint.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic on cleavages.
- 4Match the color rangeCompare against the expected color range: brown, yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular, radial, stellate.
Often confused with
Lamprophyllite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Lamprophyllite leaves pale yellow, may have an orange tint, Astrophyllite leaves golden.
How to tell apart: Eudialyte is the harder of the two (Mohs 5-6 vs. 2-3); streak differs, so Lamprophyllite leaves pale yellow, may have an orange tint, Eudialyte leaves white; luster reads submetallic on cleavages on Lamprophyllite and vitreous to dull on Eudialyte.
Often found alongside lamprophyllite
Minerals reported to co-occur with lamprophyllite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (SrNa)Ti₂Na₃Ti(Si₂O₇)₂O₂(OH)₂
- Mohs hardness
- 2-3
- Density
- 3.44-3.53 g/cm³
- Streak
- Pale yellow, may have an orange tint
- Luster
- Submetallic on cleavages
- Transparency
- Opaque, transparent to translucent in thin section
- Crystal system
- Monoclinic
- Crystal habit
- Acicular, radial, stellate
- Cleavage
- Perfect micaceous on {100}; poor on {010}
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In all rock types and most pegmatites of a differentiated alkalic massif; both polytypes coexist in ussingite-microcline-sodalite veins at Mt. Alluaiv (Lovozero massif, Russia)
Where rockhounds find lamprophyllite
Classic worldwide localities
- Rocky Boy stock, Bear Paw Mountains, Hill Co., Montana, USA
- Lovozero and Khibiny assifs, Kola Peninsula, Russia
- Konder, Inagli, and Yllymakh massifs, Yakutia, Russia
- Gardiner complex, near the head of Kangerdlugssuaq Fjord, Greenland
- Langesundsfjord, Norway
- Pilansberg, Transvaal, South Africa
Field-hunting tip
Where it forms: In all rock types and most pegmatites of a differentiated alkalic massif; both polytypes coexist in ussingite-microcline-sodalite veins at Mt. Alluaiv (Lovozero massif, Russia). If you start seeing microcline, nepheline, aegirine in float, you are in the right ground. Typical habit: acicular, radial, stellate. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify lamprophyllite?+
Where is lamprophyllite found?+
What rocks look like lamprophyllite?+
What minerals are found with lamprophyllite?+
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Find lamprophyllite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
