Alamosite is a rare lead silicate mineral that typically forms colorless to white bladed or fibrous crystal aggregates. It is most easily identified by its extremely high density and adamantine luster, often found in association with lead-rich hydrothermal mineral deposits.
Is this alamosite?
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 alamosite with a known reference. Alamosite sits at Mohs 4.5-5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Alamosite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Alamosite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: bladed crystals, fibrous masses, or radiating sprays.
Often confused with
Alamosite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside alamosite
Minerals reported to co-occur with alamosite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbSiO₃
- Mohs hardness
- 4.5-5
- Density
- 6.68 g/cm³
- Streak
- White
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Bladed Crystals, Fibrous Masses, Or Radiating Sprays
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Lead-bearing Deposits
- Typical price
- $50-500 thumbnail size specimen
Where rockhounds find alamosite
Classic worldwide localities
- Alamos, Sonora, Mexico
- Langban, Sweden
- Franklin, New Jersey, USA
Field-hunting tip
Look in hydrothermal veins in lead-bearing deposits country — that is the host setting where alamosite typically forms. If you start seeing galena, cerussite, quartz in float, you are in the right ground. Field specimens usually show a bladed crystals, fibrous masses, or radiating sprays habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find alamosite on the map
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