• A large specimen of chocolate dogtooth calcite, a lighter tan color. The top of the specimen is rounded and covered with points, and the bottom is a rough rock matrix, with a rim of broken calcite between.
  • Side view of the specimen, a large round form covered with dogtooth calcite points, on a rock matrix.
  • The backside of the specimen, a wedge of rock matrix with a rim of white broken clear calcite, then opaque brown.
  • Detail of the top of the piece, with pointy crystals radiating out. They have a mottled coating of light tan mineral that makes the piece appear lighter colored. The edge has darker crystals.
  • Close detail view of broken and cleaved crystals along the edge of the piece, with yellow-brown zoning in calcite with some translucency.
  • Detail of points on the piece with tips hollowed by etching.
  • Detail of two larger cleaved crystals, with a translucent dark triangular center and thick yellow-brown border, with some light concentric ring pattern visible.
  • Detail of a cluster of five tiny quartz points on the piece, where the calcite points meet matrix on one edge.
  • Detail of a small quartz cluster on the side of one of the calcite points. The quartz isn't super well-formed, somewhat lumpy. Above on a calcite point, there is a gap in the light-colored overgrowth along the edge where two faces meet
  • Detail of a tiny quartz cluster on the side of a calcite point, with dogtooth points well-arranged in the background.
  • Scale image of the specimen on a measuring mat, measuring almost four inches long and about two and a quarter inches wide.
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Chocolate dogtooth calcite, large

Chocolate dogtooth calcite, large

$30.00 USD
$30.00 USD
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Locale: Santa Eulalia, Chihuahua, Mexico

Approx size: 3.75 x 2.25 x 2.25"

Approx weight: 485g (about 1 lb)

 

Known by the trade name "chocolate dogtooth calcite," this type of calcite from the famed Santa Eulalia mining district grows in hedgehog clusters of sharp dogtooth (scalenohedral) crystals. The variety gets its distinctive opaque brown appearance from iron oxides; a layer of hematite-included calcite is deposited on the surface during a later phase of growth.

Broken crystals around the edge reveal the first phase of growth had some clarity with yellow-brown zoning following the crystal structure. Calcite has perfect cleavage so it is common to have a point or two that has cleaved off, leaving a flat smooth window displaying this growth. This specimen shows signs of natural etching that have left the tip of many of the dogtooth crystals blunted or hollow.

Very small crystals often dot the surface of the calcite. There is a flaky thin off-white mineral overgrowth covering a lot of the specimen, which may by calcite. Quite a few tiny points and clusters of quartz are also tucked between crystals, some with a smoky-quartz tint.

UV reactivity: the presence of iron dampens any reaction in the brown calcite, which is non-reactive. Where the strip of clear calcite is exposed along the matrix, you can get a good peachy-red reaction with some phosphorescence using 365nm UV light

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