Alforsite is a rare barium-dominant member of the apatite group that typically occurs in metamorphic environments. It is most often identified as small, colorless, hexagonal crystals or granular masses in complex mineral assemblages, particularly those found in California's Big Creek area.
Is this alforsite?
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 alforsite with a known reference. Alforsite sits at Mohs 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.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: prismatic crystals, grains.
Often confused with
Alforsite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside alforsite
Minerals reported to co-occur with alforsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ba₅(PO₄)₃Cl
- Mohs hardness
- 5
- Density
- 4.73 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Hexagonal
- Crystal habit
- Prismatic crystals, grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In lenses and bands of barium silicate metasediments developed under hornblende-pyroxene hornfels facies near the contact with granite or granodiorite
Where rockhounds find alforsite
Classic worldwide localities
- Big Creek and Rush Creek, Fresno Co., and on Trumbull Peak, near Incline, Mariposa Co., California, USA
- La Madrelena mine, Tres Pozos, Baja California, Mexico
Field-hunting tip
Where it forms: In lenses and bands of barium silicate metasediments developed under hornblende-pyroxene hornfels facies near the contact with granite or granodiorite. If you start seeing celsian, witherite, sanbornite in float, you are in the right ground. Typical habit: prismatic crystals, grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify alforsite?+
Where is alforsite found?+
Is alforsite safe to handle?+
What rocks look like alforsite?+
What minerals are found with alforsite?+
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Find alforsite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
