The mineral cerussite

Chemical Formula

PbCO₃

Composition

Lead carbonate, sometimes containing some silver and chromium

Variable Formula

(Pb,Ag,Cr)CO₃

Color

Colorless, white, gray, light yellow, and brown; may be lightly tinted blue, green, or red.

Streak

White

Hardness

3 - 3½

Crystal Forms
and Aggregates

(Orthorhombic) Commonly occurs as small, flat, thin plates, as well as prismatic and tabular crystals. Crystals frequently twin to form interesting results, such as heart, star, and v-shaped twins. An oddity is reticulated growths of thin crystals which form a delicate, snowflake-like mass. Crystal faces are usually striated. Also occurs massive, fibrous, reticulated, acicular, radiating, coxcomb, and in wheat-sheaf form. A common form is encrustations of groups of small, fragile needles.

Transparency

Transparent to translucent

Specific Gravity

6.5 - 6.6

Luster

Greasy to adamantine. Fibrous growths are silky (rare).

Cleavage

1,1 - prismatic

Fracture

Conchoidal

Tenacity

Brittle

Other ID Marks

Commonly fluorescent, usually cream-white to yellow in shortwave ultraviolet light

Other Names

Lead Spar,

White Lead Ore

In Group

Carbonates ; Aragonite group

All About

Cerussite is easily identifiable by its weight, brilliant luster, and interesting twinning habits. It also performs interesting reactions during blowpipe testing. Cerussite forms as a secondary mineral from oxidized lead deposits, particularly in arid regions. Specimens are very fragile and should be handled with extreme care.

Uses

Cerussite is an ore of lead. It is a popular mineral among collectors, especially when it forms attractive twinned crystals. Cerussite from certain locations is rich in silver and is thus used as a silver ore. Cerussite was once used as a white pigment. It is occasionally faceted into gems for collectors.

Striking Features

Luster and heaviness associated with the light color

Complex Tests

Weakly effervesces in hydrochloric acid and dissolves in nitric acid

Popularity (1-4)

Prevalence (1-3)

Demand (1-3)

Distinguishing
Similar Minerals

Calcite - lighter in weight, strongly effervesces in hydrochloric acid
Aragonite - lighter in weight (2.9 - 3.0), less brilliant in luster, and strongly effervesces in hydrochloric acid
Anglesite - doesn't effervesce at all in hydrochloric acid or dissolve in nitric acid, and never forms twinned crystals. Otherwise very difficult to distinguish.
Phosgenite - softer (2½), occurs in different crystals, fluoresces bright orange
Hemimorphite - harder (4½ - 5), crystals resembling Cerussite are restricted to only one locality where Cerussite is not found.

Commonly
Occurs With

Anglesite, Galena, Phosgenite, Azurite, Malachite, Barite, Pyromorphite, Sphalerite, Smithsonite

Noteworthy
Localities

Large single crystals, as well as v-shaped twins and intergrown "snowflakes" were found at Tsumeb, Namibia, which is perhaps the greatest locality for this mineral. Many fine crystals have come from Motevecchio and Monteponi, Sardinia, Italy; Mibladen and Touissit, Morocco; Broken Hill, New South Wales, Australia; Cornwall and Cumbria, England, and Siegerland, Germany.
In the U.S., large, single crystals occur in the Organ Mountains of Dona Ana Co. and in the Magdalena District, Socorro Co., New Mexico. In California it has been found at Cerro Gordo, Inyo Co. and in the Blue Bell Mine, San Bernardino Co. Fine specimens come from numerous Arizona localities, particularly Ajo and Tiger, Pinal Co., Bisbee, Cochise Co., and Hayden, Gila Co. Fragile white crystals, usually elongated, occur in the Flux Mine in Pantagonia, Santa Cruz Co., California. Crystal groupings with spiky crystals come the Creede District, Mineral Co., Colorado. Cerussite was once found in the Wheatley Mines of Phoenixville, Chester Co., Pennsylvania. In Canada it has been found at Selmo, British Columbia.

Picture Icon
Links

Picture Links

1. Bipyramidal Cerussite crystal
2. Fragile white Cerussite crystals