Gilalite is a rare copper silicate often found as vibrant, bright blue spherulitic clusters or needles inclusions within quartz crystals. Collectors primarily prize specimens where the mineral creates beautiful 'medusa' or 'star' patterns inside transparent quartz points.
Is this gilalite?
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 gilalite with a known reference. Gilalite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light green.
- 3Read the lusterHold the specimen under a strong light. Luster: nonmetallic.
- 4Match the color rangeCompare against the expected color range: blue green, green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous, radial, spherical.
Often confused with
Gilalite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Gilalite leaves light green, Chrysocolla leaves white when pure; luster reads nonmetallic on Gilalite and vitreous, porcelaneous, earthy on Chrysocolla.
How to tell apart: Shattuckite is the harder of the two (Mohs ~3.5 vs. 2); streak differs, so Gilalite leaves light green, Shattuckite leaves pale blue; luster reads nonmetallic on Gilalite and silky on Shattuckite.
How to tell apart: Ajoite is the harder of the two (Mohs 3.5 vs. 2); streak differs, so Gilalite leaves light green, Ajoite leaves greenish white; luster reads nonmetallic on Gilalite and vitreous on Ajoite.
Often found alongside gilalite
Minerals reported to co-occur with gilalite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₅Si₆O₁₇·7H₂O
- Mohs hardness
- 2
- Density
- 2.72 g/cm³
- Colors
- Streak
- Light green
- Luster
- Nonmetallic
- Transparency
- Transparent or translucent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, radial, spherical
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A retrograde metamorphic or mesogene mineral formed at the expense of a prograde calc-silicate and sulfide assemblage; in tactites, commonly incrusting fractures
Where rockhounds find gilalite
Classic worldwide localities
- Gila County, Arizona, USA
- Tsumeb Mine, Namibia
- Laurion, Greece
Field-hunting tip
Where it forms: A retrograde metamorphic or mesogene mineral formed at the expense of a prograde calc-silicate and sulfide assemblage; in tactites, commonly incrusting fractures. If you start seeing kinoite, apachite, stringhamite in float, you are in the right ground. Typical habit: fibrous, radial, spherical. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify gilalite?+
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Is gilalite safe to handle?+
What rocks look like gilalite?+
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Find gilalite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
