The Mineral META-ZEUNERITE

Meta-zeunerite is a dehydration product of its close cousin, zeunerite, hence the name. When the mineral zeunerite loses water and converts to meta-zeunerite, it becomes a pseudomorph. A pseudomorph is generally an atom by atom replacement of one mineral's chemistry in place of another mineral's chemistry, while the crystal's outward shape remains largely unchanged. The process leaves the crystal shape of the original mineral intact, but the original mineral is not there. Pseudomorph translated means false shape (pseudo=false; morph=shape).

In this case, the conversion is not so dramatic since it involves only the loss of a few water molecules; therefore, a good pseudomorph is likely. The conversion is irreversible and ongoing, and all collection specimens of a certain age are almost certainly partially to totally converted. If accuracy is demanded, all zeunerite collection pieces of a few years of age or more should be labeled as meta-zeunerite. Meta-zeunerite can be found naturally in nature, but probably started out as zeunerite.

The structure of meta-zeunerite is composed of arsenate tetrahedrons linked to uranium-oxygen groups that form distorted octahedrons. The arsenates and uranium groups form sheets that are weakly held together by water molecules. This structure produces the tabular habit, the one perfect direction of cleavage, and the relative softness. It is an analogous structure to that of the phyllosilicates.

Remember, this is a radioactive mineral and should be stored away from other minerals that are affected by radioactivity and human exposure should always be limited.

PHYSICAL CHARACTERISTICS:

  • Colors vary from pale to dark green.
  • Luster is vitreous to dull.
  • Transparency: Crystals are translucent to opaque.
  • Crystal System is tetragonal.
  • Crystal Habits include tabular square crystals dominated by two pinacoid faces. Bipyramidal crystals are also seen. Crystals can look cubic (pseudocubic) too. Also as crusts, micaceous, foliated and earthy. Almost all meta-zeunerite crystals are pseudomorphs of zeunerite.
  • Cleavage is perfect in one direction.
  • Fracture is uneven.
  • Hardness is 2.5
  • Specific Gravity is approximately 3.85 (above average for translucent minerals and higher than zeunerite due to loss of water molecules).
  • Streak is a pale green.
  • Other Characteristics: Radioactive, non-fluorescent and cleavage sheets are surprisingly brittle.
  • Associated Minerals are barite, fluorite, quartz, limonite, olivenite, brochantite, scorodite, meta-autunite, meta-torbernite, heinrichite, uraninite and other uranium minerals.
  • Notable Occurrences include Centennial Eureka Mine, Tintic, Utah; the Kern River uranium deposits in Kern County and near Crystal Peak in Plumas County, California and the Grandview Mine and other unanium localities in Arizona, USA; Weisser Hirsch Mine, Schneeberg, Saxony, Germany; Wheal Edward Mine, Cornwall, England and other localities with uranium arsenic minerals.
  • Best Field Indicators are color, crystal habit, non-fluorescence, higher density than zeunerite, radioactivity, associations, cleavage and brittle cleavage sheets.
META-ZEUNERITE specimens:
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META-ZEUNERITE specimen mtz-2
$ 30.00
Dims: 1.1 x 1.1 x 0.6" (2.8 x 2.8 x 1.4 cm)
Wt: 19 g w/ specimen box
Majuba Hill Mine, Pershing County, Nevada, U.S.A.
This thumbnail specimen consists of many flattened, intergrown Meta-zeunerite blades that rest on a pale brown base. These blades do not appear to exceed 0.3" (8 mm) in either length or width and are in moderately good condition, showing some damage. Their tetragonal tabular form, green color and micaceous, pearly luster are all quite similar to those of its close relatives, torbernite and meta-torbernite, though its green color is slightly duller. The specimen is affixed inside a plastic thumbnail box with a removable putty.
no photo
mtz-2 ($ 30.00)
Majuba Hill Mine, Pershing County, Nevada, U.S.A.
META-ZEUNERITE specimen mtz-3
$ 25.00
Dims: 1.0 x 0.9 x 0.5" (2.6 x 2.3 x 1.4 cm)
Wt: 6 g
Majuba Hill Mine, Pershing County, Nevada, U.S.A.
Several tiny Meta-zeunerite tablets rest on the dark brown base of this thumbnail specimen. They are generally in good condition, shnwing little damage, and do not exceed 0.1" (3 mm) in diameter. Though some appear to be intensely intergrown, those that are not show excellent tetragonal tabular form. Their grass-green color and pearly luster are very similar to that of zeunerite, torbernite, and meta-torbernite. It would appear that another secondary copper mineral is present- it is likely olivenite, which is rather commonly found at this locality. The piece is affixed inside a plastic specimen box with a removable putty.
no photo
mtz-3 ($ 25.00)
Majuba Hill Mine, Pershing County, Nevada, U.S.A.
META-ZEUNERITE specimen mtz-4
$ 50.00
Dims: 2.0 x 1.6 x 1.4" (5.2 x 4.2 x 3.6 cm)
Wt: 2.4 oz. (69 g)
Majuba Hill Mine, Pershing County, Nevada, U.S.A.
Dozens of tiny Meta-zeunerite blades rest on the shale base of this specimen. These blades appear to be in excellent condition and do not exceed 1 mm in diameter. Their tetragonal tabular form, green coloration and pearly luster make these crystals appear very similar to torbernite, though their green color is considerably paler.
no photo
mtz-4 ($ 50.00)
Majuba Hill Mine, Pershing County, Nevada, U.S.A.
META-ZEUNERITE specimen mtz-5
$ 25.00
Dims: 3.5 x 3.1 x 2.0" (8.8 x 7.9 x 5.0 cm)
Wt: 11.0 oz. (311 g)
Myler Mine, Majuba Hill, Pershing County, Nevada, U.S.A.
Several small Zeunerite crusts partly coat the base of this cabinet piece. These crusts are made up of heavily intergrown Zeunerite tablets that are generally in good condition and do not exceed 0.1" (2-3 mm) in diameter. Their tetragonal tabular form is difficult to define because of their tight intergrowth and the probability that they grew in a tight crevice. All have the standard pale green coloration and pearly luster and are likely translucent and cloudy - the tablets tend to lay flat against the base, so one cannot see light through them.
no photo
mtz-5 ($ 25.00)
Myler Mine, Majuba Hill, Pershing County, Nevada, U.S.A.
META-ZEUNERITE specimen mtz-6
$ 45.00
Dims: 2.6x1.5x1.3" (6.7x3.7x3.4 cm)
Wt: 2.7 oz. (77.2g)
Myler Mine, Majuba Hill, Pershing County, Nevada, USA
This specimen consists of a heavy sprinkling of meta-zeunerite crystals on a multi-colored rock. The meta-zeunerite crystals are very good, showing an excellent sea-foam green color. All are rectangular blades in a variety of orientations. They are opaque, and still have a vitreous luster (dull on most faces, vitreous on the edges). As a radioactive specimen, it should be handled as little as possible, and stored under glass or a plastic dome.
no photo
mtz-6 ($ 45.00)
Myler Mine, Majuba Hill, Pershing County, Nevada, USA
META-ZEUNERITE specimen mtz-7
$ 25.00
Dims: 2.76x1.35x1.17" (7.00x3.43x2.98cm)
Wt: 3.52oz (99.6g)
Myler Mine, Majuba Hill, Pershing County, Nevada, USA
This meta-zeunerite has more than a dozen clusters of small green crystals on one surface of a host rock that has at least another half-dozen minerals present. The meta-zeunerite crystals, being rather small and scattered, are at least well-formed and many of them are undamaged. In general, they are thin rectangular plates, although some of them have rounded corners.
no photo
mtz-7 ($ 25.00)
Myler Mine, Majuba Hill, Pershing County, Nevada, USA
 

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