Macquartite is a rare lead-copper chromate-silicate mineral typically found as cadmium orange, needle-like acicular crystals. It is most famous for its occurrence at the Mammoth-Saint Anthony mine in Arizona, where it forms in the oxidized zones of copper-lead ore bodies. Collectors look for its distinctive yellow acicular clusters on matrix, often associated with other rare oxidation products.
Is this macquartite?
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 macquartite with a known reference. Macquartite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale orange.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: euhedral crystals.
Often confused with
Macquartite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Macquartite leaves pale orange, Vauquelinite leaves greenish to brownish.
How to tell apart: Streak differs, so Macquartite leaves pale orange, Phoenicochroite leaves brick-red to yellowish orange.
Often found alongside macquartite
Minerals reported to co-occur with macquartite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₂Pb₇(CrO₄)₄(SiO₄)₂(OH)₂
- Mohs hardness
- 3.5
- Density
- 5.49 g/cm³
- Colors
- Streak
- Pale orange
- Luster
- Adamantine
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Euhedral crystals
- Cleavage
- Good on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- On museum specimens from an oxidized Pb-Zn-Cu orebody
Where rockhounds find macquartite
Classic worldwide localities
- Mammoth-St. Anthony mine, Tiger, Pinal Co., Arizona, USA
Field-hunting tip
Where it forms: On museum specimens from an oxidized Pb-Zn-Cu orebody. If you start seeing dioptase, quartz, willemite in float, you are in the right ground. Typical habit: euhedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find macquartite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
