selenaste

Selenaste is a fictional mineral used in discussions of mineralogy and geology as a hypothetical selenium-bearing selenide. It is described as rare and of interest largely for educational and speculative purposes rather than as a commercially important ore.

The general chemical formula of selenaste is MSe2, where M represents a transition metal such as iron, cobalt, or nickel. It crystallizes in the monoclinic system and forms prismatic to tabular crystals. The mineral typically has a metallic to submetallic luster and a gray to black coloration. It is opaque and has a hardness around 4 to 5 on the Mohs scale and a calculated density in the range of 6.5–7.2 g/cm3. Cleavage is imperfect and the fracture is uneven.

Selenaste forms under reducing conditions in hydrothermal environments, often in veins within metamorphosed, selenium-enriched host rocks. It is commonly found alongside other selenides and native selenium, and is sometimes associated with copper- or lead-bearing minerals. The mineral’s environment makes it a subject of geochemical modeling for selenium cycling in ore-forming systems.

Notable occurrences are described in speculative localities, including certain remote mountainous regions and isolated hydrothermal veins, where isolated crystals have been reported as small, well-formed aggregates or inclusions in sulfide assemblages. Because of its fictional status and rarity in educational contexts, selenaste has no established industrial use but serves as a reference point for discussions on selenium-rich mineralogy and crystallography.

The name selenaste is derived from selene, the Greek goddess of the Moon, with the -aste suffix used in mineral nomenclature for selenium-bearing compounds.