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!
"The Gonnardite/Natrolite intergrowth, was considered mesolite prior to 1988. They occur as small, opaque white hemispheres and tuffs composed of radiating fibres and prismatic needles. The individual groups have diameter up to 6 mm, though typically are 1-3 mm. The groups show a variety of lustres-chalky, sub-vitreous or silky, and prismatic needles appear quite glassy when viewed through the microscope. The clusters that have been studied are radially zoned, presenting a compact gonnardite-rich core and a soft fibrous natrolite-rich outer zone."
Boral Limited quarry, Bundoora, City of Whittlesea, Victoria, Australia