Lazaraskeite

Fig. 1. Greenish-blue prismatic crystals of lazaraskeite (polytype M2), associated with chrysocolla, muscovite, orthoclase, calcite, and quartz. Photo: Warren G. Lazar.

Fig. 2. Greenish-blue prismatic crystals of lazaraskeite (polytype M1). Field of view: 3 mm. Photo: Ron Gibbs.

For 2022 the “Mineral of the Year” award has been assigned to lazaraskeite. The mineral was discovered in the area of Oro Valley, north of Tucson, Pima County, Arizona, USA. It was found and fully characterized by a research team lead by Hexiong Yang, from the Department of Geosciences, University of Arizona, Tucson, AZ 85721-0077, USA.

More precisely lazaraskeite was found on the western end of Pusch Ridge, in the high elevation (975 m) of the Santa Catalina Mountains. where it occurs as individual crystals up to 0.2×0.2×0.8 mm or as aggregates. Crystals have a greenish-blue color, and are transparent (Fig. 1). Associated minerals are chrysocolla, malachite, wulfenite, mimetite, hydroxylpyromorphite, hematite, microcline, muscovite, and quartz.

The ideal chemical formula of lazaraskeite is Cu(C2H3O3)2. Therefore, it represents the first known example of an organic mineral containing glycolate. Shortly thereafter, three other glycolate minerals were discovered and described from the same locality: stanvevansite, jimkriegite, and lianbinite.

Lazaraskeite is monoclinic. Actually, two distinct polytypes occur, which have the same space group, P21/n, but different yet related structures. The unit cell parameters of lazaraskeite-M1 are a = 5.1049(2), b = 8.6742(4), c= 7.7566(3) Å, β = 106.834(2)°, whereas those of lazaraskeite-M2 are a = 5.1977(3), b = 7.4338(4), c = 8.8091(4) Å, β = 101.418(2)°. The crystal structures of both polytypes have been refined by single-crystal X-ray diffraction data to R = 2.6% (M1) and 2.4% (M2). The structure of lazaraskeite in both its variants is new among minerals, whereas synthetic Cu(C2H3O3)2 is known to have the same structure of polytype M1.

The mineral name is a composite after the names of the two mineral collectors who found it, Warren G. Lazar and Beverly Raskin. 

The state of Arizona is confirmed as the seat of beautiful and interesting crystals, since another mineral from Arizona got the “Mineral of the Year” award in 2017: rowleyite, after the Rowley mine, Maricopa County.

The full description of the new mineral has been published in the American Mineralogist [Yang, H., Gu, X., Gibbs, R., Evans, S., Downs, R.T., Jibrin, Z. (2022): Lazaraskeite, Cu(C2H3O3)2, the first organic mineral containing glycolate, from the Santa Catalina Mountains, Tucson, Arizona, U.S.A. American Mineralogist, 107, 509-516].