Taseqite
Chemical formula: Na<sub>12</sub>Sr<sub>3</sub>Ca<sub>6</sub>Fe<sup>2+</sup><sub>3</sub>Zr<sup>4+</sup><sub>3</sub>Nb<sup>5+</sup>Si<sub>25</sub>O<sub>73</sub>(O,OH,H<sub>2</sub>O)<sub>3</sub>Cl<sub>2</sub>
Taseqite is a rare, beige-brown mineral from the eudialyte group, discovered in the Ilímaussaq igneous complex in Greenland.
Properties
- Mohs hardness
- 5
- Luster
- Vitreous
- Streak
- White
- Density
- 2.96
- Cleavage
- None
- Fracture
- Uneven
- Transparency
- Translucent
- Crystal system
- Trigonal
Diagnostic features
## Identification Field identification of taseqite is practically impossible due to its small size and resemblance to other minerals of the eudialyte group. Definitive identification requires advanced analytical techniques, such as X-ray microanalysis (EDS/WDS) to determine its unique chemical composition, especially its high strontium and niobium content. ## Distinguishing from Similar Minerals It can be confused with other minerals from the eudialyte group, such as eudialyte itself, kentbrooksite, or oneillite. Differentiation relies solely on precise chemical analysis, which reveals specific elemental proportions, including the dominance of niobium over titanium and a characteristic strontium-to-calcium ratio. ## Crystal Forms Taseqite occurs as anhedral, or irregular, grains embedded in the rock. Well-formed crystals have not been observed.
Geological environment
## Genesis Taseqite is a mineral of magmatic origin. It forms in the late stages of crystallization within highly differentiated, alkaline nepheline syenite intrusions. Its occurrence is restricted to the specific geochemical conditions prevalent in the Ilímaussaq complex. ## Mineral Associations This mineral occurs in association with other rare alkaline minerals. It most commonly co-occurs with microcline, nepheline, aegirine, sodalite, eudialyte, arfvedsonite, as well as more exotic minerals such as nacareniobsite-(Ce), steenstrupine-(Ce), and vitusite-(Ce). ## Localities The only confirmed locality for taseqite worldwide is its type locality: the Ilímaussaq alkaline complex, specifically the Taseq area, in southern Greenland.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of a taseqite specimen is determined not by the taseqite itself (which is microscopic), but by the richness and aesthetics of the entire mineral assemblage. The most desirable specimens are those with clearly visible, numerous taseqite grains accompanied by well-formed crystals of other rare minerals, such as eudialyte or steenstrupine. Precise analytical documentation confirming the presence of taseqite is also crucial. ## Popular Localities The only source of specimens is the Ilímaussaq complex in Greenland. These specimens are extremely rare on the market and primarily go to specialized collections of rare minerals and scientific institutions.
Care and storage
## Cleaning Due to the small size of the grains and their occurrence within the host rock, mechanical cleaning of individual crystals is usually impossible. When cleaning an entire rock specimen, it is recommended to use a soft, dry brush to remove dust. ## What to Avoid Contact with strong acids and chemicals should be avoided, as they could damage both taseqite and its associated minerals. There is no detailed data on sensitivity to light or temperature, but standard caution is advised, as with other collectible minerals. ## Storage Specimens containing taseqite should be stored in stable conditions, away from dust and moisture, preferably in sealed boxes or display cabinets. A label with precise locality information is crucial due to the mineral's scientific significance.