Scawtite is a rare calcium silicate carbonate mineral typically found in metamorphosed limestone deposits. Collectors look for its characteristic platy habit or massive formations in hydrothermal contact zones. It is most famous for its discovery at the Scawt Hill locality in Northern Ireland.
Is this scawtite?
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 scawtite with a known reference. Scawtite 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. 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: monoclinic. Typical habit: platy.
Often confused with
Scawtite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside scawtite
Minerals reported to co-occur with scawtite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₇Si₆O₁₈(CO₃)·2H₂O
- Mohs hardness
- 4.5-5
- Density
- 2.71 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy
- Cleavage
- {010}, fair; {100}, poor
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- A late-stage hydrothermal mineral veining skarns formed from contact metamorphism of limestone
Where rockhounds find scawtite
Classic worldwide localities
- Crestmore, Riverside Co., California, and near Neihart, Cascade Co., Montana, USA
- Scawt Hill and Ballycraigy, near Larne, Co. Antrim, Ireland
- Zeilberg, near Maroldsweisach, Bavaria, Germany
- Kushiro, Hiroshima Prefecture, and in the Mihara mine and at Fuka, near Bicchu, Okayama Prefecture, Japan
- Rehia, Tokatoka district, about 150 km north of Auckland, New Zealand
Field-hunting tip
Where it forms: A late-stage hydrothermal mineral veining skarns formed from contact metamorphism of limestone. If you start seeing melilite, spurrite, tobermorite in float, you are in the right ground. Typical habit: platy. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify scawtite?+
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Find scawtite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
