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Boulangerite with Arsenopyrite

The Mineral boulangerite




Boulangerite typically forms in a unique crystal habit of fine acicular crystals that appear as woven, hair-like fibers. The thin fibers, which can be very thick covering an entire specimen, or thinly spaced on a matrix, are often bent or interwoven due to their flexibility. Boulangerite also forms as dense, hairy inclusions within other crystals, especially Calcite and Quartz. Boulangerite often forms together with the chemically similar mineral Jamesonite, and may be very difficult to visually distinguish from it. Boulangerite is named after Charles Louis Boulanger (1810-1849), a French mining engineer.
Chemical Formula Pb5Sb4S11
Composition Lead antimony sulfide
Color Lead-gray with a bluish tint. May occasionally tarnish with an iridescent film.
Streak Brownish gray to black
Hardness 2.5 - 3
Crystal System Monoclinic
Crystal Forms
and Aggregates
Most often in acicular or interlocking masses of long hair-like crystals. Also fibrous, plumose, radiating, in compact fibrous masses, in interconnected thin slender crystals, and in massive form. An unusual habit is cylindrical rings and hollow tubes that form as a result of microscopic crystal fibers spinning naturally in a concentric pattern during formation.
Transparency Opaque
Specific Gravity 6.2 - 6.3
Luster Metallic
Cleavage 2,1
Fracture Uneven to splintery
Tenacity Brittle. Thin fibers flexible
In Group Sulfides; Sulfosalts
Striking Features Color, crystal habits, and flexibility
Environment Low temperature hydrothermal replacement deposits.
Rock Type Sedimentary
Popularity (1-4) 3
Prevalence (1-3) 3
Demand (1-3) 2


Boulangerite ON EBAY
OTHER NAMES
Feather Ore May refer to either Boulangerite or Jamesonite due to their prevalent habit forming in feathery crystal aggregates.
Mullanite

VARIETIES
 -  Feathery, plumose form of Boulangerite.


USES
Boulangerite is a minor ore of lead.

NOTEWORTHY LOCALITIES
One of the best localities for Boulangerite is the Noche Buena Mine, Mazapil, Zacatecas, Mexico. This locality has produced excellent examples of fibers in dense habit associated within a matrix with other ore minerals. The Yaogangxian Mine, Yizhang Co., Hunan Province, China, produces dark Boulangerite crystals of very large size, associated with Quartz, as well as included within the Quartz.

Eastern Europe has several classic localities for Boulangerite, where it occurs in the typical, hair-like habit. These include Příbram, Bohemia, Czech Republic; the Trepča complex, Kosovo; and the Herja Mine, Baia Mare, Maramureș Co., Romania (where the Boulangerite is often densely including Calcite crystals. Western European localities of note are the Ramsbeck District, North Rhine-Westphalia, Germany; La Mure, Isère, Rhône-Alpes, France; and the Bottino Mine, Stazzema, Tuscany, Italy.

Boulangerite is uncommon in the U.S. The two most important deposits are the Coeur d'Alene district, Shoshone Co., Idaho; and the Cleveland Mine, Stevens County, Washington. Canada has produced Boulangerite, especially in odd tubular form, at the Rogers Mine, Madoc, Hastings Co., Ontario.

COMMON MINERAL ASSOCIATIONS
Stibnite, Galena, Pyrite, Arsenopyrite, Quartz, Siderite, Calcite, Dolomite, Fluorite, Sphalerite

DISTINGUISHING SIMILAR MINERALS
Jamesonite - Lacks flexible fibers.
Millerite - Color is more yellowish.


boulangerite PHOTOS
 
ADDITIONAL RESOURCES
 
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