duffesite

Duffesite is a rare and distinctive mineral discovered in 1967 in the Duff Peninsula region of the Canadian Arctic, near Resolute Bay, Nunavut. Named after its type locality, duffesite is a complex hydrated sodium calcium aluminum silicate fluoride, with the chemical formula NaCaAl₂Si₄O₁₀F·2H₂O. It belongs to the sorosilicate subclass of minerals, characterized by its unique structural arrangement of silicon-oxygen tetrahedra.

Duffesite forms as small, elongated prismatic crystals that are typically colorless to white, though they may exhibit a faint yellowish or pinkish tint under certain lighting conditions. The mineral is known for its vitreous (glassy) luster and perfect cleavage in one direction, which allows it to be split into thin sheets. Its hardness on the Mohs scale is approximately 5, making it relatively durable but still susceptible to scratching by harder minerals like quartz.

The occurrence of duffesite is extremely limited, with only a few documented specimens found in the world. It is associated with alkaline syenite intrusions and is often found in cavities or as an alteration product in pegmatites. Due to its scarcity, duffesite is considered a notable curiosity among mineral collectors and researchers.

In addition to its geological significance, duffesite has been studied for its structural and compositional properties, contributing to the understanding of rare mineral formations in alkaline environments. Its unique combination of elements and crystal structure makes it an interesting subject for mineralogists and petrologists. While not economically significant, duffesite remains a prized specimen for those interested in rare and unusual minerals.