Macphersonite
Macphersonite, Pb42 2, is a carbonate mineral that is trimorphous with leadhillite and susannite. Macphersonite is generally white, colorless, or a pale amber in color and has a white streak. It crystallizes in the orthorhombic system with a space group of Pcab. It is fairly soft mineral that has a high specific gravity.
Macphersonite is named after Harry Gordon Macpherson, a keeper of minerals at the Royal Scottish Museum. It was discovered and accepted in 1984.
Structure
The structure of macphersonite is represented as a sequence of three layers stacked along the . The first layer is a sulfate tetrahedra, the second is of lead and hydroxide, and the third is a layer composed of lead and carbonate. Stacking of the three layers can be detailed as...BABCCBABCC... similar to leadhillite. Two C layers of lead carbonate in the BAB stacking provide a weak connection that leads to the perfect cleavage.Physical properties
The Leadhills macphersonite is a very pale amber to colorless in color, while the Argentolle mine macphersonite is colorless to white. It has a luster of adamantine on fresh surfaces and elsewhere it is resinous. Macphersonite is soft with a 2.5-3 on the Mohs hardness, has an uneven fracture with a high density of 6.5g/cm3.Macphersonite has a very strong yellow fluorescence under both long and short wave, ultraviolet is displayed by the Leadhills specimens, the Argentolle material does not fluoresce.