Lanarkite , Susannite , Macphersonite Locality: Susanna Mine (Glennery Scar Vein; Susanna Vein (Scar Vein); Portobello Vein; Humby Vein; Lead Vein), Leadhills , South Lanarkshire , Strathclyde (Lanarkshire) , Scotland , UK ( Locality at mindat.org ) Size: 4 x 3 x 2 cm This specimen is absolutely superb for several reasons: its richness, history, and crystal size among them. It is a large cluster of already remarkable lanarkite crystals from the type locality. The lanarkites are draped with a druse of susannite crystals (also type locality) to 3mm - considered extremely rich overall. A small yellow macphersonite crystal is attached at the front (looks like a little yellow wulfenite, center-middle in photo). This specimen is a major classic rarity of the mid to late 1800s, seldom seen in this quality even in the most major Museum collections. The piece was exchanged out of the collection of France's National Museum of Natural History and made its way into the Lindsay and Patricia Greenbank collection (of English and Scottish minerals) by the 1990s. It was bequeathed to the museum in about 1900 as dated by the antique museum accession label in the handwriting of Professor Alfred Lacroix. It had been in the noted collection of Charles Frossard, a noted French collector living in the Pyrenees, by the end of the 1800s. Joe Budd photos. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Macphersonite
A white-to-amber lead sulfate-carbonate trimorphous with leadhillite and susannite.
Intro adapted from Wikipedia (CC BY-SA).
Macphersonite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Pb₄(SO₄)(CO₃)₂(OH)₂.
It crystallizes in the orthorhombic crystal system (space group Pbca).
Key properties: Mohs hardness 2.5–3; specific gravity 6.5–6.55; Adamantine to resinous luster; optically biaxial.
IMA symbol Mps, IMA status: approved, named in 1982.
Occurs as an uncommon secondary mineral in the zone of oxidation of lead deposits.
It is found associated with Leadhillite, susannite, cerussite, caledonite, pyromorphite, scotlandite, mattheddleite, galena, quartz.
The mineral was named to honor Dr. Harry Gordon Macpherson (1925–), Keeper of Minerals, Royal Scottish Museum, Edinburgh, Scotland.