• A large specimen held in a hand, approximately the size of two fists. The piece is chaotic, dark iron oxides form a craggy surface with many pockets and folds, and a wedge of orange-tinted rock matrix is at the center, next to a small hole where you can see through the center of the specimen. There are patches of a golden yellow and a colorless mineral on the piece, interspersed with the red rock and near-black matrix.
  • Labeled with "365nm UV light," the image shows the specimen in the dark, fluorescing under a blue-tinted light. Small square crystals spot the surface in dense patches, appearing like bright yellow spots.
  • Side-view of the specimen, with a patch of minerals in focus. A narrow gap in the side is lines with calcite over wulfenite, with dark matte botryoidal crystals forming the upper edge, with exposed patched of wulfenite above.
  • The back side of the specimen, which features less yellow wulfenite, and more dark botryoidal iron oxides. There is a patch of brown-colored wulfenite squares at the bottom.
  • Side-view of the specimen, with shards of red-tinted soft rock and irregular masses of dark iron oxides. A strip across the center is filled with calcite over wulfenite.
  • Detail of a patch of wulfenite, very small square tablet crystals, some fat enough to look like cubes. They are arranged in all directions.
  • Labeled with "365nm UV light," a detail of the same are of the specimen from the previous image but in the dark, fluorescing under a blue-tinted light. A patch of well-formed but tiny square tablets of wulfenite fluoresces bright yellow, with milky-appearing calcite crystals around them.
  • Detail of a fang-like protrusion on the specimen, covered with near-black botryoidal iron oxides. The spheres appear as if dusted with mustard color, with very small square tablet crystals of wulfenite sprinkled across the surface. Some crystals have the two main faces slightly lighter in color, so the center strip appears darker like a sandwich. Colorless calcite crystals partially cover the area, one appearing yellow from the wulfenite encased inside.
  • Detail of a patch of the surface with square wulfenite crystals, some flat tablets and some thick like cubes. The area has a brownish color almost like tarnished pyrite. Two larger calcite crystals grow on the wulfenite.
  • Detail image showing a pocket in the folds of the surface of the specimen, with botryoidal iron oxides covered with thick yellow wulfenite, and a layer of colorless calcite crystals. The crystals are broken in cross-section along the red rock on the lower left, appearing a black bumps with a rim of yellow and white crystal.
  • Very close detail of colorless calcite crystals, the interiors a golden yellow from the wulfenite inside. The crystals are angular, with some in the center left giving some faint rainbows of iridescence.
  • Detail of a formation that looks like two matte tan lumpy balls, peppered with small wulfenite crystals and with several long angular calcite crystals atop.
  • Detail of the two lumpy balls formation from above, the calcite crystal with kite-shaped faces. A large colorless crystal is on the surface below them, with yellow wulfenite visible inside. Well-formed tiny wulfenite crystals sprinkle the surface in the left bottom, some with color zoning.
  • Very close detail image of a sphere of coronadite with a colorless calcite crystal on the surface, surrounded by calcite above and with a craggy black surface below it.
  • Detail of flat hexagonal platelets of colorless crystal intersecting in clusters
  • Close detail of an area of botryoidal coronadite coated in a mustard-yellow layer of amorphous wulfenite, with small square crystals sprinkles on the surface.
  • Scale image of the piece on a measuring mat, measuring about five inches wide and four inches tall
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Calcite and wulfenite on iron oxide matrix

Calcite and wulfenite on iron oxide matrix

$28.00 USD
$32.00 USD $28.00 USD
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Locale: Glove Mine, Santa Cruz County, Arizona

Approx size: 5 x 4 x 2.5"

Approx weight: 672g (almost 1 1/2 lb)

** Brittle warning! This material is brittle and may shed pieces, use caution when handling.

** Staining warning! The soft oxidized matrix will leave dark dusty staining on surfaces and your skin.

 

This specimen from the Glove Mine in southern Arizona looks messy and chaotic at first glance, but it is an excellent piece for studying the details—best for someone with good eyesight! There are crystals tucked in the nooks and crannies, and you can find examples of several characteristics typical of the locale.

The matrix is a soft weathered iron oxide referred to as gossan, which also appears to incorporate botryoidal coronadite. Wulfenite formed next, adding a mustard-yellow coating to the botryoidal growth, and sprinkling tiny yellow crystals across the surface. A later phase of calcite growth encased much of the wulfenite inside glittering, colorless crystals.

The wulfenite crystals are flat or pseudo-cubic square tablets, some featuring a faint version of the color-zoned 'sandwich' habit common to this region (where the main faces are slightly lighter in color like a slice of bread on each side of a darker center). Wulfenite from the Glove Mine commonly is also commonly a dark brown-black, either from pseudomorphing or from iron oxide inclusions. There is a small patch of brown wulfenite crystals with a slightly sub-metallic luster on this specimen, shown in the detail images.

UV reactivity: Wulfenite from some regions can fluoresce, and this is a neat example of it! You realize just how much wulfenite coats the specimen when you get it under 365nm UV light, and large patches fluoresce with golden yellow spots. 

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