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

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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.