From: Palmarejo Mine, Chihuahua, Mexico
Size: 9.5 x 17.3 x 8.1cm
There are many forms of calcite mineral specimens in the world, but none so immediately identifyable as the multigenerational twinned calcites from the Palmarejo Mine in Mexico. One look at these and you know exactly what it is and where it came from because there are no other calcite specimens in the world that look anything like this!
These specimens first started appearing in 2014, but most hit the market in 2017. Even then it was unclear exactly what these were, so most dealers labled them simply as calcite. Recent reseach, however, has revealed exactly what these are and how they formed, and there is an entire article with all of the details in the Sept/Oct 2018 Issue of Rocks & Minerals magazine. According to this research these specimens started as elongated "fish-tail" twinned calcite crystals. Later, more layers of manganese rich calcite were deposited. After this is when things got interesting because there was a uni-directional flow in the cavity where these formed, and this caused a thin, white layer of Palygorskite to form just on one side of the specimen - the side facing the flow. It seems that nothing else could grow on top of the Palygorskite, so subsequent generations of minerals were only deposited on the uncoated surfaces. The thin black layer you see around the white palygorskite is Romanechite, and then after that a new layer of clear/brown calcite was deposited.
This particular specimen is special because it forms a really apparent heart shape with perfect symmetry and aesthetics. The vast majority of these calcite specimens are, well, ugly and damaged. This is one of the few that are in excellent condition with great aesthetics. It's really one of the top examples we've ever seen which is why we acquired it. The main twin calcite crystal is exceptionally large, and the last-generation calcite on the back is clear with some manganite inclusions while the tips are light brown. Even the bottom is caoted with glassy-clear crystals. This is one of the best Palmarejo calcite specimens out there!
The specimen comes with a labeled acrylic display base.