Cerussite Identification Guide

What Cerussite Looks Like

Cerussite is lead carbonate, a secondary mineral of the oxidized zones of lead deposits. It is usually colorless, white, or gray, sometimes tinted yellow or brown, and is famous for a brilliant adamantine (near-diamond) to resinous luster. Crystals are orthorhombic and frequently form striking twins, including V-shapes, star-shaped sixlings, and reticulated lattice networks. The standout property is its extreme heaviness due to lead.

Key Visual Traits

• Brilliant adamantine, almost diamond-like luster
• Colorless, white, or gray; often transparent to translucent
• Distinctive twinned crystals (V-twins, snowflake sixlings, lattices)
• Extremely heavy in the hand

Step-by-Step Field-ID Checklist

1. Heft it first. Cerussite is shockingly heavy (SG about 6.5); the weight alone narrows it dramatically.
2. Note the luster. Adamantine, brilliant, sparkling, not dull.
3. Test hardness. Soft, Mohs 3 to 3.5; a knife scratches it.
4. Look for twinning. V-shaped or star-shaped twins and lattice intergrowths are highly diagnostic.
5. Acid test. Effervesces in warm dilute hydrochloric acid (it is a carbonate); reaction may be sluggish cold.
6. Check the setting. Found with galena and other lead-zinc oxidation minerals.

Diagnostic Tests

• Hardness: 3 to 3.5 (scratched by a knife).
• Cleavage: Distinct but often hard to see in twinned crystals; brittle, conchoidal fracture.
• Streak: White (colorless to white).
• Density: Very high, about 6.5; among the heaviest common collector minerals.
• Acid: Fizzes in warm dilute HCl (carbonate).
• Luster: Adamantine to resinous.

Common Look-Alikes and How to Tell Them Apart

• Anglesite (lead sulfate): Also heavy and bright and associated with lead deposits, but it does NOT effervesce in acid; cerussite fizzes because it is a carbonate. The acid test separates them.
• Barite: Heavy and can be bright, but lower density (SG about 4.5) and gives a green flame; barite does not fizz in acid.
• Calcite: Fizzes in acid too, but is far lighter (SG 2.7) and has rhombohedral cleavage and a glassy, not adamantine, luster.
• Phosgenite: Closely related lead mineral; needs careful work to separate, but cerussite's twinning and acid response help.
• Quartz/topaz: Much harder (7 to 8) and far lighter.

Where It Is Typically Found

Cerussite forms in the oxidized (weathered) zones of lead ore deposits, derived from the alteration of galena. Superb specimens come from Tsumeb (Namibia), Touissit (Morocco), Broken Hill (Australia), and many districts in the United States (Arizona, Colorado, New Mexico). It is an important ore of lead and a favorite of collectors for its brilliance and complex twins.

Collector and Field Notes

Cerussite is fragile as well as soft, so its brilliant twinned crystals chip and cleave with rough handling; cushion specimens well. The reticulated lattice twins and snowflake sixlings from Tsumeb and Morocco are among the most sought-after collector pieces. Always treat it as a lead-bearing mineral: avoid dust, do not handle it near food, and wash your hands afterward. For a fast field confirmation, pair the extreme weight and adamantine sparkle with a warm dilute acid test, where slow effervescence confirms a carbonate and separates it immediately from the otherwise similar sulfate anglesite.