THE MINERAL BAUMHAUERITE

Chemistry: Pb₃As₄S₉, Lead Arsenic Sulfide
Class: Sulfides
Subclass: Sulfosalts
Uses: As a very minor ore of lead and arsenic and as mineral specimens.
Specimens

Baumhauerite is a rare sulfide mineral from the famous quarry at Lengenbach, Binnental, Valais, Switzerland. The site is famous for many rare minerals including: novakite, rathite, smythite, dufrenoysite, jordanite, marrite, seligmannite, wallisite, lengenbachite, bernardite, sartorite, arsenolamprite, liveingite, imhofite and hatchite to name a few. Most of the more exotic minerals from this site are arsenic sulfides and sulfosalts like baumhauerite. Baumhauerite is usually a bright dark gray mineral with a nice luster and striated prismatic crystals embedded in a dolomitic marble. It is a rare mineral and is only found in a few localities. Lengenbach is the only locality where specimens can be found with regularity.

PHYSICAL CHARACTERISTICS:

Color is a bright lead gray, blue gray to gray black (internal reflections will flash a red color).
Luster is metallic to dull.
Transparency: Crystals are opaque.
Crystal System: Triclinic; bar 1.
Crystal Habits include prismatic striated crystals with rounded faces; also in massive and granular forms.
Cleavage: Indistinct.
Fracture: Conchoidal.
Hardness is 3.
Specific Gravity is 5.3 (slightly heavier than average for metallic minerals)
Streak is dark brown.
Associated Minerals include dolomite, realgar and sartorite.
Notable Occurrences are limited to the type locality of the Lengenbach Quarry, Binnental, Valais, Switzerland and Franklin, New Jersey, USA.
Best Field Indicators are crystal habit, locality, internal reflections, associations and density.