Boothite is a rare copper sulfate mineral that typically forms as bright blue, fragile crusts or fibrous efflorescences in mine workings. It is highly unstable in dry air, as it easily loses water to convert into other copper sulfate phases, making well-preserved specimens highly prized by mineral collectors.
Is this boothite?
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 boothite with a known reference. Boothite sits at Mohs 2-2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, silky or pearly if fibrous.
- 4Match the color rangeCompare against the expected color range: blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive.
Often confused with
Boothite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside boothite
Minerals reported to co-occur with boothite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuSO₄·7H₂O
- Mohs hardness
- 2-2.5
- Density
- 1.94 g/cm³
- Colors
- Streak
- Pale blue
- Luster
- Vitreous, silky or pearly if fibrous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Massive
- Cleavage
- {001}, imperfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An alteration product of chalcopyrite (Alma mine, California, USA)
Where rockhounds find boothite
Classic worldwide localities
- Alma pyrite mine, near Leona Heights, Alameda Co., and from the Penn (Campo Seco) mine, Calaveras Co., California, USA
- Colusa mine, Butte, Silver Bow Co., Montana, USA
- Sain-Bel, near Lyon, Rhône, France
- Galaktos district, 15 km southeast of Veria, Greece
- Tolbachik fissure volcano, Kamchatka Peninsula, Russia
Field-hunting tip
Where it forms: An alteration product of chalcopyrite (Alma mine, California, USA). If you start seeing chalcanthite, melanterite, pisanite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify boothite?+
Where is boothite found?+
Is boothite safe to handle?+
What rocks look like boothite?+
What minerals are found with boothite?+
What kind of rock does boothite form in?+
What is boothite used for?+
Find boothite on the map
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