Name/Title
Wulfenite / Mimetite / BariteEntry/Object ID
2009.62.126Description
Chemical Composition: Lead Molybdate
Crystal System: Tetragonal System
Description: Common Name: Wulfenite / Mimetite / Barite
Chemistry: PbMoO4, Lead Molybdate / Pb5(AsO4)3Cl, Lead Chloroarsenate / BaSO4, Barium Sulfate
Class: Sulfates / Phosphates / Sulfates
Location: San Francisco Mine, Sonora, Mexico
Description: A large grouping of irregular plate shaped crystals ranging in color from translucent gold to yellow with some dull white bladed Barite crystals also mixed in. The whole crystal grouping is attached to a large course grained, yellow, orange, and violet matrix.
PHYSICAL CHARACTERISTICS OF WULENITE:
Color is red, orange, yellow, silver and white.
Luster is vitreous.
Transparency: Crystals are transparent to translucent.
Crystal System is tetragonal; 4/m or 4
Crystal Habits include very thin square or octahedral pinacoidal plates with pyramidal faces truncating just the edges of the crystal. At times the pyramids become prominant and psuedo-dipyramidal crystal habits are seen, sometimes because of twinning. Prismatic faces are also seen and can make psuedo-cubic crystals. Also encrusting and cavernous aggregates due to intergrowth of crystal plates.
Cleavage is perfect in one direction.
Fracture is conchoidal.
Hardness is 3.
Specific Gravity is approximately 6.8 (very heavy for translucent minerals)
Streak is white.
Associated Minerals are mimetite, limonite, smithsonite, vanadinite and galena.
Other Characteristics: index of refraction is 2.28-2.40 (very high, but typical of lead minerals).
Best Field Indicators are crystal habit, color, density and luster.
PHYSICAL CHARACTERISTICS OF MIMETITE:
Color is typically yellow, orange or brown, less commonly green, colorless or gray.
Luster is resinous to adamantine.
Transparency: Crystals are transparent to translucent.
Crystal System is hexagonal; 6/m
Crystal Habits include the barrel shaped hexagonal prism with the hexagonal pyramid and/or a pinacoid as a termination. more commonly found as classic botryoidal crusts, sparkling aggregations that resemble cauliflower, small attached spherical masses or as minute spike-like crystals.
Cleavage is rarely noticed.
Fracture is subconchoidal.
Hardness is 3.5 - 4.
Specific Gravity is approximately 7.1+ (very heavy for translucent minerals)
Streak is off white.
Associated Minerals are wulfenite, limonite, calcite, barite, galena and secondary lead deposit minerals.
Other Characteristics: Index of refraction is 2.13 (typically high for lead minerals) and crystal terminations can be hollowed out or pitted.
Best Field Indicators are crystal habit, high luster, color, and density.
PHYSICAL CHARACTERISTICS OF BARITE:
Color is variable but is commonly found colorless or white, also blue, green, yellow and red shades.
Luster is vitreous.
Transparency crystals are transparent to translucent.
Crystal System is orthorhombic; 2/m 2/m 2/m
Crystal Habits include the bladed crystals that are dominated by two large pinacoid faces top and bottom and small prism faces forming a jutting angle on every side. There are many variations of these faces but the flattened blades and tabular crystals are the most common. If the pinacoid faces become diminished or are absent, the resulting prismatic crystal has a rhombic cross section. Also scaly, lamellar, and even fiberous.
Cleavage is perfect in one direction, less so in another direction.
Fracture is conchoidal.
Hardness is 3 - 3.5
Specific Gravity is approximately 4.5 (heavy for translucent minerals)
Streak is white.
Associated Minerals are numerous but significant associations have been with chalcopyrite, calcite, aragonite, sulfur, pyrite, quartz, vanadinite, cerussite and fluorite among many others.
Other Characteristics: green color in flame test (see above).
Best Field Indicators are crystal habit, flame test and density.
Fracture: Conchoidal
Hardness: 3 Calcite
Luster: Vitreous
Occurrence: Wulfenite crystallizes in the tetragonal system, often occurring as stubby, pyramidal or tabular crystals. It also occurs as earthy, granular masses. It shows a white streak and has a hardness of 2.75 - 3.0 on Mohs scale of mineral hardness. It is a dense mineral, with a specific gravity of 6.5-7.0.
Rock Type: Sedimentary
Specific Gravity: 6.8
Streak: whiteCollection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Width
5-1/4 inDepth
4-1/2 inLength
4-1/4 inWeight
2.12 ozLocation
Location
Container
LeftDrawer
Bottom / 2nd RowShelf
Left, LeftWall
West wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Steve MillerDate
January 30, 2010Location
Drawer
far leftShelf
bottom front left, bottom front leftWall
West wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Scott LonganDate
September 26, 2009Location
Cabinet
G-3 rearWall
NorthBuilding
Storage (old gift shop upstairs)Category
Permanent