THE MINERAL WOLFEITE

  • Chemistry: (Fe, Mn)2PO4OH, Iron Manganese Phosphate Hydroxide
  • Class: Phosphates
  • Uses: Mineral specimens.
  • Specimens

Wolfeite is a rare and obscure mineral. It is found in altered granite pegmatites with other rare phosphate minerals. It is important to note that the iron and manganese ions in wolfeite are in the positive two (+2) oxidation state. This is a reduced state from most altered iron and manganese minerals that contain these ions in the positive three (+3) oxidation state. This is important because the presence of wolfeite indicates that the iron and manganese have not undergone extensive oxidation. Wolfeite may be an intermediate between minerals such as hornblende which contains iron at a positive two state and higher oxidized phosphates such as purpurite. Wolfeite, whose name could easily be confused with both wolframite and wulfenite is a nice rare mineral with a rather high luster and interesting color that any collector would love to own.

PHYSICAL CHARACTERISTICS:

  • Color is reddish to dark brown.
  • Luster is vitreous to adamantine or even greasy.
  • Transparency crystals are rarely transparent, but more commonly translucent.
  • Crystal System is monoclinic; 2/m
  • Crystal Habit is generally prismatic crystals or fibrous aggregates.
  • Cleavage is absent.
  • Fracture is uneven.
  • Hardness is 4.5 - 5
  • Specific Gravity is approximately 3.8+ (above average)
  • Streak is white.
  • Other Characteristics: Crystals are striated vertically.
  • Associated Minerals include quartz, feldspars, purpurite, hureaulite, dicksonite and other phosphates found in altered granite pegmatites.
  • Notable Occurrences include Custer Co., South Dakota and Palermo Mine, New Hampshire, USA and Bavaria, Germany.
  • Best Field Indicators are color, crystal habit, striations, associations and luster.
WOLFEITE specimens:
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WOLFEITE specimen wof-1
$ 60.00
Dims: 2" x 1" x 1-3/8"
Wt: 2.87 oz
Big Fish River, Yukon, Canada
This little chunk of rock is hard to explain; I don't know how the person that found it knew what it was. First, the rock appears to be in a nodular type of form, with the outer surface colored black and polished to an almost waxy luster from weathering or water wear. When the "nodule" was broken open, the cross-section revealed that it was solid, containing red-brown fibrous crystals that are densely compact, with a pearly luster. Whoever found it must just know what to look for, or maybe it has something to do with the specimen's weight- it is pretty dense. All I know is that there aren't an awful lot of them around. The specimen is affixed to a small acrylic base with a hot-melt glue or rubber cement.
no photo
wof-1 ($ 60.00)
Big Fish River, Yukon, Canada
WOLFEITE specimen wof-2
$ 60.00
Dims: 1-7/8" x 1-3/8" x 1-1/8"
Wt: 3.1 oz
Big Fish River, Yukon, Canada
Wolfeite is likely identified according to its locality and its density, because the outsides of the specimens from the Big Fish River locality in Canada don't look at all like the insides! The specimen's exterior is somewhat nodular in form and seems to exhibit some concentric layering. It is basically black colored and it has some whitish patches that may denote weathering, and some rust staining. The interior is a different story, however; it consists of tightly-packed crystals that are almost fibrous in appearance, but make me think more that they would look like thin blades if they were loose. The interior's color is brown with just a hint of red, and the material seems to be translucent, although there is no way that light could penetrate the rough exterior. Some of these crystals span the height of the specimen, attaining lengths of 1-3/4 inches. I find this material to be rather interesting, especially with its deceiving coating.
no photo
wof-2 ($ 60.00)
Big Fish River, Yukon, Canada
WOLFEITE specimen wof-3
$ 53.00
Dims: 2.5" x 1.3" x 1.6" (6.4 x 3.3 x 4.1 cm)
Wt: 4.18 oz. (118.9 g)
Big Fish River, Yukon, Canada
This specimen consists of part of a Wolfeite "nodule" that has been broken open. Its outer surface has been worn relatively smooth and is coated with a thin layer of a dull, pale brown material that makes for a very deceiving appearance. The specimen's broken area, however, reveals the mineral's bladed crystal form and compact, radiating habit. It has a deep brown coloration and a bright, pearly luster, and could be translucent or even dimly transparent if the crystals were separated.
no photo
wof-3 ($ 53.00)
Big Fish River, Yukon, Canada
WOLFEITE specimen wof-4
$ 100.00
Dims:2.4x1.4x1.4" (6.1x3.6x3.6 cm)
Wt: 3.1oz. (87g)
Boundary Creek, Near Yukon/NWT Boundary, Canada
This specimen is half of a nodule of fibrous, radiating wolfeite crystals. Wolfeite crystals reach 1.2" (3.0cm) in length. The exterior of the nodule is coated with a rusty-brown alteration rind due to weathering. There is no significant damage to this specimen.
no photo
wof-4 ($100.00)
Boundary Creek, Near Yukon/NWT Boundary, Canada

 


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