Hydroxylellestadite is a complex member of the apatite group that features sulfate and silicate groups in its structure. It typically occurs in contact metamorphic zones, specifically within skarns where it forms through the interaction of limestone with igneous intrusions. Collectors often find it as small prismatic crystals associated with other silicate minerals in skarn assemblages.
Is this hydroxylellestadite?
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 hydroxylellestadite with a known reference. Hydroxylellestadite 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. Hydroxylellestadite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Hydroxylellestadite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray, pale yellow.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: prismatic crystals, granular, massive.
Often confused with
Hydroxylellestadite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside hydroxylellestadite
Minerals reported to co-occur with hydroxylellestadite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₁₀(SiO₄)₃(SO₄)₃(OH)₂
- Mohs hardness
- 4.5-5
- Density
- 2.9-3.0 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Hexagonal
- Crystal habit
- Prismatic Crystals, Granular, Massive
- Cleavage
- Indistinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Skarns and Metamorphosed Limestone Deposits
- Typical price
- $20-150 per specimen
Where rockhounds find hydroxylellestadite
Classic worldwide localities
- Bazhenovskoye deposit, Russia
- Kopeysk, Russia
- Velardena, Mexico
- Franklin, New Jersey, USA
Field-hunting tip
Look in skarns and metamorphosed limestone deposits country — that is the host setting where hydroxylellestadite typically forms. If you start seeing calcite, diopside, grossular in float, you are in the right ground. Field specimens usually show a prismatic crystals, granular, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hydroxylellestadite?+
Where is hydroxylellestadite found?+
How much is hydroxylellestadite worth?+
What rocks look like hydroxylellestadite?+
What minerals are found with hydroxylellestadite?+
What kind of rock does hydroxylellestadite form in?+
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Find hydroxylellestadite on the map
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