Gmelinite PS Chabazite
Posted by: macadmin on 04.20.2020 | Filed under:

Gmelinite PS Chabazite

Specimen # 101509
Mineral: Gmelinite PS Chabazite
Location: Five Islands, Cumberland Co., Nova Scotia, Canada
Size: 3.5 x 2.6 x 2.1 cm


Detailed Description

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.

Situated in the Five Islands, in the Bay of Fundy, this locality is a classic, described in reports in Canada and the U.S. dating back to the 19th century. Specimens from Pinnacle Island (albeit as “Pinnack Island”) are included in Victor Goldschmidt’s famous early 20th century Atlas der Krystallformen. Pinnacle Rock produced spectacular specimens in 2004 and 2006 (the specimens here were among them). Unfortunately, a major area where specimens were found has now collapsed into the Bay of Fundy and has been washed away by the sea.

Additional information

Dimensions 35 × 26 × 21 cm