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 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Gilalite leaves a pale blue streak.
- 3Read the lusterHold the specimen under a strong light. Gilalite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, pale blue, turquoise.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: spherulitic, acicular, fibrous.
Often confused with
Gilalite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Gilalite leaves pale blue, Chrysocolla leaves white.
How to tell apart: Shattuckite is the harder of the two (Mohs 3.5 vs. 2.5); streak differs — Gilalite leaves pale blue, Shattuckite leaves blue; luster reads vitreous on Gilalite and dull on Shattuckite.
How to tell apart: Ajoite is the harder of the two (Mohs 3.5 vs. 2.5).
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
- 2.5
- Density
- 2.7-2.8 g/cm³
- Streak
- Pale Blue
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Spherulitic, Acicular, Fibrous
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-500 thumbnail
Where rockhounds find gilalite
Classic worldwide localities
- Gila County, Arizona, USA
- Tsumeb Mine, Namibia
- Laurion, Greece
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where gilalite typically forms. If you start seeing quartz, chrysocolla, malachite in float, you are in the right ground. Field specimens usually show a spherulitic, acicular, fibrous habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find gilalite on the map
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