Adelite is a relatively rare calcium magnesium arsenate mineral typically found in metamorphosed manganese deposits. It most commonly occurs in botryoidal, crusty, or massive habits, occasionally showing distinct yellowish-green to gray-green coloration and a characteristic yellow fluorescence under short-wave UV light.
Is this adelite?
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 adelite with a known reference. Adelite 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. Adelite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Adelite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, grayish-green, yellowish-green, white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: crusts, botryoidal, massive, sometimes as small prismatic crystals.
Often confused with
Adelite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside adelite
Minerals reported to co-occur with adelite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMgAsO₄OH
- Mohs hardness
- 5
- Density
- 3.73 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Crusts, Botryoidal, Massive, Sometimes as Small Prismatic Crystals
- Cleavage
- None
- Fluorescence
- Yellow Under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphosed Manganese Ore Deposits
- Typical price
- $20-150 for thumbnail to small cabinet specimens
Where rockhounds find adelite
Classic worldwide localities
- Langban, Sweden
- Nordmark, Sweden
- Franklin, New Jersey, USA
- Sterling Hill, New Jersey, USA
Field-hunting tip
Look in metamorphosed manganese ore deposits country — that is the host setting where adelite typically forms. If you start seeing calcite, dolomite, hausmannite in float, you are in the right ground. Field specimens usually show a crusts, botryoidal, massive, sometimes as small prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
More adelite photos
Common questions
How do you identify adelite?+
Where is adelite found?+
How much is adelite worth?+
Is adelite safe to handle?+
What rocks look like adelite?+
What minerals are found with adelite?+
What kind of rock does adelite form in?+
What is adelite used for?+
Find adelite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
