• A large piece of aragonite and calcite in indirect sunlight. it is an off-rectangular shape with bumps and valleys on the surface. The front covered with opaque matte rough-textured points, in a pale tan color.
  • Detail of a round cluster of points, with the crust coating the points appearing composed of flat platelets of growth.
  • Another angle of the front of the piece, showing rounded forms covered with points radiating out.
  • Angled view of the large piece, with a white matrix side visible and some white overgrowth on the edge of the top.
  • Side-view of the specimen with rough white matrix and the crust-like layer of points on the right side. Hollows can be seen in the partial points along the edge.
  • Detail of the side of the piece, showing the points are on a crust-like layer on top of the matrix, hollowed out beneath
  • Two sides of the piece with rough white rock matrix and a small pocket in one end.
  • A flat end of the piece, rough pale matrix
  • Scale image of the piece on a measuring mat, measuring almost four inches long and tapered from less than an inch to abut three inches wide.
1 9

Aragonite and calcite

Aragonite and calcite

$28.00 USD
$28.00 USD
Sale Sold out
Shipping calculated at checkout.

Locale: Sidi Ayed, Fès-Meknès Region, Morocco

Approx dimensions: 3.75 x 2.5 x 2

Approx size: 700g (1.5 lb)

 

Calcite and aragonite are polymorphs of one another, meaning that the same chemical composition (calcium carbonate) has crystallized into different crystal structures (trigonal and orthorhombic, respectively). Calcite and aragonite often grow together, and the two minerals are also frequent paramorphs of one another—a pseudomorph of the same chemical composition and retaining the original crystal shape but with different crystal structure, created through a change of conditions such as heat or pressure. There is understandably some confusion distinguishing what is calcite, versus aragonite, or a paramorph, or some hodgepodge of all of the above.

Which is all to say, this specimen falls somewhere in that ‘hodgepodge’ category. It appears aragonite formed over calcite points which then partially dissipated, leaving some hollow between layers. This specimen is especially good as an inexpensive accent piece for your collection; it is large with well-formed points, and has flat surfaces on the back that help it self-stand for display.

View full details