Cerussite
Current inventory:  3 gems
 

  
Cerussite is named from the Latin word cerussa, meaning white lead.

Discovered in 400 BC;   IMA status:  Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

PbCO₃

Lead Carbonate

Molecular Weight:

267.21. gm

Composition:

Lead

77.54 %

Pb

83.53 %

PbO

Carbon

4.49 %

C

16.47 %

CO₂

Oxygen

17.96 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Carbonates

Strunz 8th Ed. ID:

5/B.04-40

Nickel-Strunz 10th Ed. ID:

5.AB.15

5 : CARBONATES (NITRATES)
A : Carbonates without additional anions, without H₂O
B : Alkali-earth (and other M²⁺) carbonates

Related to:

Aragonite Group.

Members of Group:

Aragonite Group: Aragonite, Cerussite, Strontianite, Witherite

Varieties:

Argentiferous Cerussite, Chrome-Cerussite, Zincian Cerussite

Synonyms:

Acrusite, Black Lead Ore, Carbonate of Lead, Cerusite, Lead Spar, White Lead, White Lead Ore

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Crystals, to 0.6 m, are tabular, equant to elongated, or pseudohexagonal dipyramidal, exhibiting many combinations. Also granular, pulverulent, stalactitic, as randomly intergrown prismatic aggregates, rarely fibrous, massive.

Twinning:

Common; as simple or cyclic contact twins, producing stellate pseudohexagonal or reticulated composites; as contact twins producing heart-shaped composites. Both laws may occur in one aggregate.

Physical Properties

Cleavage:

Distinct on {110} and {021}, Poor on {010} and {012}

Fracture:

Conchoidal

Tenacity:

Very Brittle

Moh's Hardness:

3.0 - 3.5

Density:

6.53 - 6.58 (g/cm³)

Luminescence:

Fluorescent. May fluoresce yellow to golden-yellow or white under LW UV, also under X-rays.

Radioactivity:

Not Radioactive

Other:

Soluble in dilute HNO3 with effervescence.

Health Warning:

CAUTION: Contains Lead. Wash hands after handling. Do not lick or ingest; do not inhale dust when breaking. Do not grind dry.

Optical Properties

Color:

Colorless, White, pale Yellow, smoky to dark Gray, Blue, Green, Black with inclusions

Transparency:

Transparent to Translucent

Luster:

Adamantine, Vitreous, Resinous, Pearly, Dull, Earthy

Refractive Index:

1.804 - 2.079  Biaxial ( - )

Birefringence:

0.2740 (very high)

Dispersion:

0.055; Relatively Strong; r > v (greater than diamond)

Pleochroism:

None

Occurances

Geological Setting:

Common in the oxidized zone of lead deposits, where it may constitute an important ore.

Common Associations:

Anglesite, Galena, Limonite, Malachite, Phosgenite, Pyromorphite, Silver, Smithsonite

Common Impurities:

None

Type Locality:

Vicenza Province, Veneto, Italy

Year Discovered:

400 BC

View mineral photos:

Cerussite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Cerussite is a very rare and very beautiful gem that is a lead carbonate. It is a member of the Aragonite group of minerals that also includes Aragonite and Witherite. A Cerussite gem can be as beautiful as a diamond since it has very high dispersion (greater than a diamond), is usually colorless and has an adamantine luster. Its high dispersion, high luster and high density are due to its lead content. Just as leaded crystal glass has more sparkle and brilliance because of its lead content, so does Cerussite. Cerussite crystals are abundant but Cerussite is one of the most difficult gems to facet due to its softness (3.0-3.5), its brittleness and its high heat sensitivity. Therefore, faceting Cerussite is extremely difficult and time consuming. Many break in the process. Few gem cutters have the time, patience, skill and tender loving care to deal with faceting Cerussite. Because of this, faceted Cerussite is one of the rarest of all gems. The high cost of a faceted Cerussite is mostly due to the cost of faceting, not the cost of the rough material.

Two of the most notable occurances of facetable Cerussite crystals are Touissit mine, near Oujda, Morocco and Tsumeb, Namibia.
 

  
Cerussite gems for sale: