Cerussite is an important mineral and significant ore of lead. It is chemically a mineral made up of lead carbonate (PbCO3) and the cerussite ore is a significant ore of lead. The name of the mineral is derived from the Latin word cerussa, which means white lead. The commonly used names of the cerussite ore during early discovery and excavation are lead-spar and white-lead-ore used by the miners in the mining industry. The present form of the cerussite ore terminology is the one given by W. Haidinger, an Australian mineralogist in 1845. An image of the crystal of cerussite mineral is shown below:
[Image will be uploaded soon]
Cerussite Properties and Characteristics
The crystallisation of cerussite gemstone or cerussite stone leads to an orthorhombic system and is isomorphous with aragonite. The aragonite is a very frequently twinned crystal. According to mineralogy, when two separate crystals have crystal lattice points in a similar manner, it is known as crystal twinning. Due to crystal twinning there is an intergrowth of the two separate crystals in different specific configurations. Hence, the type of twinning becomes an identification factor for a mineral. Hence, as mentioned above like the aragonite crystal, the cerussite mineral or cerussite gemstone show twinning and the compound crystal forms of the cerussite mineral, are pseudo-hexagonal in formation.
Some of the Physical Properties of Cerussite Gemstone/Mineral is Listed Below:
The Cerussite crystal formation process includes twinning which gives it a typical pattern which is also an identification factor of the mineral. In cerussite, three crystals are twinned together, on the two faces of the prism. This results in a six-rayed stellate group in which the individual crystals are intercrossing at angles of nearly 60°.
These crystals are very bright and have smooth faces. Most of the cerussite crystals found show these physical properties of brightness and smoothness.
Cerussite mineral occurs in two different types of forms. They are: compact granular masses form and fibrous forms. Both the forms are adequately found at their specific mineral sites.
The mineral is also known for being colorless or white, although sometimes it may contain grey or greenish tint and can vary from being transparent to translucent along with an adamantine lustre.
The structure of the mineral does not follow any natural planes of separation and because of this it is brittle and breaks with a conchoidal fracture i.e. with smooth and curved surfaces typically slightly concave and showing concentric undulations.
The specific gravity of the mineral is 6.5.
For testing of the mineral it can be recognised as it dissolves in nitric acid with effervance. A blow-pipe test causes it to fuse rapidly and gives the indication of the presence of lead in the mineral.
Forms and Locations of Cerussite Mineral
Finely crystallized specimens have been obtained from the Friedrichssegen mine in Lahnstein in Rhineland-Palatinate, Johannegeorgenstadt in Saxony, Stribo in Czech Republic, Phoenixville in Pennsylvania, Broken Hill in New South Wales, and other different localities. Acicular (fine needle-like) crystals that are delicate and are of considerable length were found in Pentire Glaze mine near St. Minver in Cornwall. The mineral can also be found at sites where there is a mixture of crystals such as cerussite barite galena, which are crystals made up of lead, barium and galena, respectively.
Cerussite is often found in quantities with a lead content of upto 77.5%. There is also a variety of cerussite containing 7% of zinc carbonate instead of lead carbonate and this mineral form is known as Iglesiasite, from Iglesias in Sardinia, where it is found. Lead (II) carbonate which is the main component of the mineral is practically insoluble in neutral water, but will not dissolve in dilute acids.
Usage of Cerussite
“White lead”, the common name of cerussite, has been a main ingredient in the preparation of lead paints. These paints have been used in oil-paints that have been used for house paintings or in art exhibition paintings, and also in water based paints. But as the use of lead paints decreased because of the increasing lead poisoning cases in children due to the ingestion of lead-based paint chips. Along with paints, both the “white lead” and lead acetate have been used very commonly in cosmetics throughout history but the current trends have shown decreased or ceased in the lead-based cosmetic applications at least in western countries.