Calcite and wulfenite on iron oxide matrix

Calcite and wulfenite on iron oxide matrixLocale: 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

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.