Mccrillisite is an extremely rare phosphate mineral known primarily from the Mount Mica pegmatite in Maine. It typically forms as small, tabular crystals associated with other phosphate minerals in complex pegmatitic environments.
Is this mccrillisite?
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 mccrillisite with a known reference. Mccrillisite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Mccrillisite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Mccrillisite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: pink, colorless, white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals.
Often confused with
Mccrillisite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside mccrillisite
Minerals reported to co-occur with mccrillisite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaBe₂PO₄F₂
- Mohs hardness
- 3.5
- Density
- 2.8 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular Crystals
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- varies significantly by specimen availability
Where rockhounds find mccrillisite
Classic worldwide localities
- Mount Mica pegmatite, Maine, USA
Field-hunting tip
Look in granite pegmatites country — that is the host setting where mccrillisite typically forms. If you start seeing beryllonite, eosphorite, herderite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find mccrillisite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
