A pair of interlocking crystals of gmelinite after chabazite with good colour and top lustre – these are sharp, glassy crystals. In excellent condition, no damage to the main crystals, a contact at lower front of the piece (which, interestingly, reveals some underlying chabazite). Collected in 2004. Stands perfectly for display as photographed in the first photo. The second photo is taken from what is “above” in the first photo, and the third is angled to show the back, and show that the shadowy area in the second photo is actually fully crystallized (gmelinite is just a funny mineral to photograph – if you don’t bounce the light right off it, it looks dull and irregular).
About These Gmelinites
Truly great, display-quality specimens of gmelinite are known from very few localities worldwide. These specimens of gmelinite from Pinnacle Rock are exceptional for the mineral – brilliant glassy lustre, sharp, with fantastic, intricate crystallization patterns.
The mode of occurrence has been described as “gmelinite on chabazite” and also “gmelinite after chabazite”. These specimens are comprised of a crystallized layer of gmelinite over chabazite, so that the overall shape is the rhombohedral chabazite form. Most of these retain a chabazite core to some degree, although often the chabazite can be quite porous, and some specimens are partial epimorphs, where the original chabazite core area has at least partially dissolved away altogether, leaving hollow spaces inside the outer gmelinite crystal layer. Given the overall exterior chabazite form, they are “gmelinite pseudomorphs after chabazite”, however it is important to distinguish that these are not gmelinite as a mere replacement material: the beautiful crystallization of the gmelinite prominently displays morphological habits and growth patterns, and it is these brilliant gmelinite crystal growths and overgrowths that make these specimens special.
These specimens are gmelinite-Na, as analyzed by the RRUFF Project.