Tetragonita

Tetragonita is a rare mineral species that belongs to the zeolite group. It was first discovered in 1976 in the Tetragonal Valley, near the town of Poudrette, Quebec, Canada, which is the type locality for this mineral. The name "tetragonita" is derived from the Greek word "tetra" meaning four, and "gonita" meaning angles, referring to the four-sided crystals that are characteristic of this mineral.

Tetragonita typically forms as a secondary mineral in cavities within basaltic rocks, often associated with other zeolites such as chabazite and analcime. It is usually colorless or white, but can also be found in shades of yellow, brown, or gray due to impurities. The mineral has a hardness of 4.5 to 5 on the Mohs scale and a specific gravity of approximately 2.2 to 2.3.

The crystal structure of tetragonita is characterized by its four-sided prismatic crystals, which can reach up to 1 cm in length. The mineral is monoclinic in crystal system and has a chemical formula of (Na,K,Ca)4-6[Al6Si10O32]·12H2O. It is an important indicator mineral for the presence of rare earth elements and other valuable minerals in certain types of rocks.

Tetragonita is not commonly found in mineral collections due to its rarity and the difficulty in locating suitable specimens. However, it is of significant interest to geologists and mineralogists for its unique crystal structure and its potential as an indicator mineral for valuable deposits.