Bobmeyerite is a rare lead aluminum copper silicate that forms colorless to white or cream-colored tapered acicular crystals. It is a secondary mineral in the oxidized zone of a polymetallic sulfide deposit. It was first described from Mammoth-St. Anthony mine, Tiger, Pinal County, Arizona, USA.

Hardness

4-5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent to translucent

mineralrareTundrite Group family

Bobmeyerite

Hardness: 4-5
Luster: Vitreous
Streak: White
Transparency: Transparent to translucent

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Is this bobmeyerite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch bobmeyerite with a known reference. Bobmeyerite sits at Mohs 4-5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: colorless, white, cream-colored.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tapered acicular crystals.

Often confused with

Bobmeyerite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Astrophyllite

Mohs 3

How to tell apart: Bobmeyerite is noticeably harder (Mohs 4-5 vs. 3); streak differs, so Bobmeyerite leaves white, Astrophyllite leaves golden; luster reads vitreous on Bobmeyerite and submetallic, pearly, greasy on Astrophyllite.

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Often found alongside bobmeyerite

Minerals reported to co-occur with bobmeyerite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Pb₄(Al₃Cu)(Si₄O₁₂)(S₀.₅Si₀.₅O₄)(OH)₇Cl(H₂O)₃
Mohs hardness: 4-5
Density: 4.381 g/cm³
Colors: Colorless WhiteCream-colored
Streak: White
Luster: Vitreous
Transparency: Transparent to translucent
Crystal system: Orthorhombic
Crystal habit: Tapered acicular crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral in the oxidized zone of a polymetallic sulfide deposit

Where rockhounds find bobmeyerite

Classic worldwide localities

Mammoth-St. Anthony mine, Tiger, Pinal County, Arizona, USA

Field-hunting tip

Where it forms: A secondary mineral in the oxidized zone of a polymetallic sulfide deposit. If you start seeing atacamite, caledonite, cerussite in float, you are in the right ground. Typical habit: tapered acicular crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify bobmeyerite?+

Mohs hardness is 4-5. Luster: vitreous. The streak is white. Common colors include colorless, white, cream-colored.

Where is bobmeyerite found?+

Notable localities include Mammoth-St. Anthony mine, Tiger, Pinal County, Arizona, USA.

Is bobmeyerite safe to handle?+

Bobmeyerite contains copper and lead. Contains lead, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust.

What rocks look like bobmeyerite?+

Bobmeyerite is most often confused with Astrophyllite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with bobmeyerite?+

Bobmeyerite commonly co-occurs with Atacamite, Caledonite, Cerussite, Connellite, Diaboleite, Fluorite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does bobmeyerite form in?+

Where it forms: A secondary mineral in the oxidized zone of a polymetallic sulfide deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is bobmeyerite used for?+

Bobmeyerite is used in collector.

Find bobmeyerite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.