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!
Specimens of metasomatically altered natromontebrasite, collected at the Strickland quarry around 1950 by Charles Thomas, consist of gray augelite crystals intergrown with pink brazilianite, pink hydroxylapatite, and yellow lacroixite. Very little such material was preserved, and most of it was consumed in study at the U.S. Geological Survey. Natromontebrasite was discredited in 2007, being a mixture of montebrasite, lacroixite, and wardite.