Plumbogummite

Formula: PbAl3(PO4)2(OH)5·H2OMohs scale hardness: 4(4,5)-5Specific gravity: 4,014

Plumbogummite is a rare secondary lead phosphate mineral, belonging to the alunite supergroup of minerals, crandallite subgroup. Some other members of this subgroup are:

  • Crandallite, CaAl3(PO4)2(OH)5·H2O, where calcium replaces lead

  • Goyazite, SrAl3(PO4)(OH)5·H2O, where strontium replaces lead

  • Philipsbornite, PbAl3(AsO4)2(OH)5·H2O, where the arsenate group AsO4 replaces the phosphate group PO4

Plumbogummite is found in the oxidized zones of lead-bearing deposits. It commonly occurs as botryoidal, kidney shaped, stalactitic or globular crusts or masses, frequently with a concentric structure; rare crystals have a hexagonal outline. Pyromorphite and baryte are common associated minerals, and plumbogummite may be pseudomorphic after them. Other associated minerals include mimetite, duftite, cerussite, anglesite and wulfenite.

Plumbogummite has been found in the Central Cobar Mines, New South Wales, Australia and the Nifty Copper Mine, Western Australia. Also in the Kintore open cut at Broken Hill, New South Wales, Australia.

References

  1. https://en.wikipedia.org/wiki/Plumbogummite

  2. http://www.irocks.com/galleries/plumbogummite-china-fine-minerals