Cerussite - Encyclopedia

    Class : Carbonates, nitrates, borates
    Subclass : Anhydrous carbonates
    Crystal system : Orthorhombic
    Chemistry : PbCO3
    Rarity : Common

Cerussite is the most common oxidized lead mineral and is found in the oxidation zones of lead deposits. It results from the alteration of the galena, often with an intermediate passage through the anglesite, unstable in the presence of CO32- ions. Its development is all the more important as the country is carbonated and the climate arid. It takes its name from the latin cerussa (white lead), name given by Pliny the Elder for synthetic lead carbonate. The cerusite occurs in crystals (sometimes very large) elongated, often flattened, prismatic, pseudohexagonal, also in double pseudohexagonal pyramids (pseudoisechoedrons). They are frequently twinned and can produce spectacular reticulated samples with 60° and 120° angles, or more rarely heart-shaped or "V" twins. Cerusite also consists of compact or earthy masses and sometimes skeletal stalactitic slats. Translucent to transparent in crystals, almost opaque in masses, the cerusite has a high characteristic density (more than 6.5). Pure, it is colorless with an adamantine luster, but it is frequently blackened by inclusions of galena, or colored in gray, yellow, green, blue or red by metallic oxides. Cerusite is an important lead ore, and is also highly appreciated by mineral collectors.

Reticulated cerussite from Nakhlak Mine, Anarak District, Esfahan, Iran
Cerussite from Touissit, Morocco

Twinned cerussite from M'Fouati, Congo
Twinned cerussite from M'Fouati, Congo

Cerussite in the World

The most spectacular specimens of cerusite are undoubtedly the "V" twins, yellow-pink more than 10 cm and the reticulated aggregates of more than 25 cm extracted from the Kombat and Tsumeb mines in Namibia, but also the magnificent decimetric twinned crystals from Touissit in Morocco. Broken Hill's Australian mine also provided excellent crystals and reticulated groups. Superb specimens were also extracted from the superficial area of lead deposits of Monteponi (Italy), Dundas (Tasmania), Beresovsk (Urals), and American deposits in Arizona. More recently, Iran (Nakhlak Mine) has also produced outstanding white decimetric reticulated pieces.
Cerussite from Mayres, Ardèche, France
Cerussite from Villefranche-de-Rouergues, Aveyron, France
Cerussite from Villefranche-de-Rouergues, Aveyron, France
Cerussite from Villefranche-de-Rouergues, Aveyron, France

Cerussite in France

In France, centimetric crystals have been discovered in several deposits, such as Mayres (Ardeche), Villefranche-de-Rouergues (Aveyron), Farges (Correze), Chaillac (Indre), the most famous being Pontgibaud (Puy-de -Dome).

Twinning and special forms

The twins are universal for this species. Most of the time on {110} and sometimes cyclic, they can generate stars (photo on the right), pseudo-hexagonal or reticular sets. On {130} twins are less common, it generates a heart shape. Both types can coexist on the same sample.

Fakes and scams

There are no fake records for this species.

Hardness : 3 to 3.5
Density : 6.6
Fracture : Conchoidal
Trace : White

TP : Transparent to opaque
IR : 1.803 to 2.076
Birefringence : 0.273
Optical character : Biaxe -
Pleochroism : Weak
Fluorescence : Yellow,white, blue, green

Solubility : Nitric acid

Magnetism : None
Radioactivity : None