Search Mineralpedia – A Mineral Photo Database and Identification Guide
Named in honor of Professor Samuel Lewis Penfield, a mineralogist and mineral chemist at Yale University in Connecticut, USA. Penfieldite is a rare mineral found in Greece, Italy, and Chile among a couple other localities and forms as “an alteration product of lead-bearing slag immersed in seawater” and in oxidized lead deposits of hydrothermal origin. Penfieldite is soluble in water and leaves behind a yellow-white lead-oxychloride residue.
Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/penfieldite.pdf
Named after the Lapp words used to describe its usual appearance: penk, meaning “curly,” and vilkis, meaning “white.” Penkvilkisite can be found only in the Jubilee pegmatite in the Lovozero massif in the Kola Peninsula, Russia, and at Mont Saint-Hilaire in Quebec, Canada. At the type locality in the Jubilee pegmatite, Penkvilksite occurs in the natrolite zone of the pegmatite, and at Mont Saint-Hilaire it occurs in a pegmatite vein cutting a marble xenolith.
Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/penkvilksite.pdf
Name is actually a misnomer for the composition which was originally described as having five (penta) water molecules per each formula unit. A rare mineral found only in Russia, Serbia, Japan, and possibly Kazakhstan. Pentahydoborite occurs as a mineral in boron bearing iron ore skarn and in volcanogenic sedimentary borate deposits. Pentahudroborite will fluoresce a purple-violet color under long-wave ultraviolet light.
Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/pentahydroborite.pdf