Cassidyite is a rare phosphate mineral found in oxidized nickel-rich environments. Collectors typically look for its distinctive pale green, tabular crystals often occurring in radiating clusters or thin crusts.
Is this cassidyite?
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 cassidyite with a known reference. Cassidyite sits at Mohs 4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Cassidyite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Cassidyite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, yellowish-green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, radiating aggregates, crusts.
Often confused with
Cassidyite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside cassidyite
Minerals reported to co-occur with cassidyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaNi₂(PO₄)₂(OH)₂·2H₂O
- Mohs hardness
- 4
- Density
- 2.85 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Radiating Aggregates, Crusts
- Cleavage
- Good On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Nickel-bearing Hydrothermal Veins and Oxidized Zones of Ore Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find cassidyite
Classic worldwide localities
- Woods Mine, Pennsylvania, USA
- Santa Eulalia District, Mexico
- Reaphook Hill, Australia
Field-hunting tip
Look in nickel-bearing hydrothermal veins and oxidized zones of ore deposits country — that is the host setting where cassidyite typically forms. If you start seeing goethite, annabergite, schorl in float, you are in the right ground. Field specimens usually show a tabular crystals, radiating aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cassidyite?+
Where is cassidyite found?+
How much is cassidyite worth?+
What rocks look like cassidyite?+
What minerals are found with cassidyite?+
What kind of rock does cassidyite form in?+
What is cassidyite used for?+
Find cassidyite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
