Vote for your favorite mineral in #MinCup26! - Sphalerite vs. Anorthite Both zinc ore Sphalerite and calcium plagioclase feldspar Anorthite have perfect cleavage that will split cleanly if you hit them with a hammer, but only one can claim a larger split of your votes!
Schooner (circa 1985) reports: "A few years ago, John Gillespie did a spectrographic analysis on a sample submitted by the author, finding much Na and hardly any Li. It is quite possible that natromontebrasite was fairly common... A few masses of Strickland quarry natromontebrasite, from the pollucite zone in the middle eastern wall, halfway down, are composed of intergrown metasomatic or hydrothermal alterations. Pink brazilianite, containing a trace of Mn (analysis by the USGS), is associated with augelite, lacroixite, and hydroxylapatite. This mineral was collected by Charles Thomas, and studied by Mary E. Mrose [USGS]." This mineral was discredited in 2007 as a mixture of montebrasite, lacroixite and wardite.