Number 8 Turquoise is a highly sought-after collector variety famous for its distinct, often spidery black or brownish limonite matrix against a vibrant blue or light green backdrop. It originated from a now-depleted mine in Eureka County, Nevada, making authenticated specimens increasingly rare and valuable. Collectors prize the high-grade material for its aesthetic 'spiderweb' pattern and historical significance in Southwestern lapidary arts.
Is this number 8 turquoise?
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 number 8 turquoise with a known reference. Number 8 Turquoise sits at Mohs 5-6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: waxy.
- 4Match the color rangeCompare against the expected color range: blue, green, spiderweb matrix.
- 5Look at form & habitCrystal system: triclinic. Typical habit: massive.
Often confused with
Number 8 Turquoise vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads waxy on Number 8 Turquoise and vitreous to waxy on Variscite.
How to tell apart: Number 8 Turquoise is noticeably harder (Mohs 5-6 vs. ~2-4); luster reads waxy on Number 8 Turquoise and vitreous, porcelaneous, earthy on Chrysocolla.
Often found alongside number 8 turquoise
Minerals reported to co-occur with number 8 turquoise. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuAl₆(PO₄)₄(OH)₈·4H₂O
- Mohs hardness
- 5-6
- Density
- 2.6-2.8 g/cm³
- Streak
- White
- Luster
- Waxy
- Transparency
- Opaque
- Crystal system
- Triclinic
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Gemstone, Lapidary, Collector
- Host rock
- hydrothermal veins in sedimentary rock
Where rockhounds find number 8 turquoise
Classic worldwide localities
- Eureka County, Nevada
- Carlin Trend, Nevada
Field-hunting tip
Where it forms: hydrothermal veins in sedimentary rock. If you start seeing quartz, kaolinite, limonite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
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Find number 8 turquoise on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
