• A large rounded specimen of chocolate calcite with large dogtooth crystals pointing outward, and smaller rounded spiky forms at the base. The specimen is opaque with a desaturated brown color, matte with some sheen.
  • Detail of the side of the specimen, the surface rough and dark brown, with patches of orange iron staining. Several points have etching marks in the tips.
  • Angled view of the specimen, which has one large sphere of crystals pointing outward, with some smaller rounded forms of points at the base. There is orange iron staining around the base of some points.
  • The backside of the specimen, a strip of broken crystal down the back of the sphere as if it once attached there, with a carve plate of crystals at the base. a lumpy lighter brown mineral runs vertically across the face.
  • Angled view focused on a cluster of large, well-formed points that are close to the base. Nearby, a broken edge appears light-colored.
  • Detail view focused on a large calcite point that has cleaved off, leaving a flat surface. Inside, it has some translucency, with concentric bands of yellow-brown zoning, and dark brown edges. The points around it are spotted with orange iron staining, and a filmy, flaky white layer of mineral overgrowth.
  • Detail of a flower-like formation of calcite points fanning out like petals around an irregular growth. The points have striations etched into the surface, giving them almost bone-like texture. The calcite nearby has a reflective sheen.
  • Detail of a lumpy halo of quartz formed on a calcite point, with a small quartz point growing off it. The format has a light orange tint or iron staining.
  • The underside of the specimen, a circle of rock matrix visible, ringed by thick broken opaque brown calcite crystals around it. There is a second smaller round form to the bottom right.
  • Detail of an edge of the piece showing heavy evidence of crystal dissolution, with raised edges of crystals around hollow interiors and concentric patterns etched inside crystals.
  • Scale image of the piece on a measuring mat, measuring about four inches wide and three inches tall.
1 11

Chocolate dogtooth calcite, large

Chocolate dogtooth calcite, large

$26.00 USD
$26.00 USD
Sale Sold out
Shipping calculated at checkout.

Locale: Santa Eulalia, Chihuahua, Mexico

Approx size: 4 x 3 x 2.5"

Approx weight: 652g (about 1 1/3 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 reveal the first phase of growth had some translucency with yellow-brown zoning in the interior. 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 has left the tip of many of the dogtooth crystals blunted or hollow. Very small crystals often dot the surface of the calcite. A lot of the specimen is covered with a flaky thin off-white mineral overgrowth, which may by calcite. Tiny points of quartz often spot these specimens; this piece has a disc-like botryoidal quartz formation on one calcite crystal, with two small quartz points growing off it.

UV reactivity: the presence of iron dampens any reaction in the brown calcite, which is non-reactive. This piece has limited reaction.

View full details