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

mineralrareTundrite Group family

Bobmeyerite

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

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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. Bobmeyerite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Bobmeyerite typically shows a vitreous luster.
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-brown; luster reads vitreous on Bobmeyerite and submetallic 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 White Cream-colored
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Tapered Acicular Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Nepheline Syenite

Where rockhounds find bobmeyerite

Classic worldwide localities

Magnet Cove, Arkansas, USA

Field-hunting tip

Look in nepheline syenite country, the host setting where bobmeyerite typically forms. If you start seeing aegirine, nepheline, orthoclase in float, you are in the right ground. Field specimens usually show a tapered acicular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify bobmeyerite?+

Mohs hardness is 4-5. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white, cream-colored.

Where is bobmeyerite found?+

Notable localities include Magnet Cove, Arkansas, USA.

Is bobmeyerite safe to handle?+

It contains toxic constituents. Contains lead, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust. Handle with care, avoid grinding or breathing dust, and store separately.

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 Aegirine, Nepheline, Orthoclase, Titanite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does bobmeyerite form in?+

Bobmeyerite typically forms in nepheline syenite. 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.