Mineralpedia Details for Penfieldite

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

Formula

Pb₂Cl₃(OH) 

Crystal System

Hexagonal 

Crystal Habit

Pyramidal, Tabular 

Cleavage

Distinct, None, None 

Luster

Adamantine - Greasy 

Color

colorless, white, yellowish, bluish 

Streak

white 

Class

Hexagonal - Dihexagonal Dipyramidal 

Hardness

3-4 

WebMineral

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Mindat

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Doubly terminated from 0.5 to 2mm, white to clear or light blue and striated associated with Boleite as micro coatings.