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!
Bridges et al. (2008): "two specimens of typical material were analysed by XRD in this study. One was a pale turquoise blue specimen with occasional desiccation cracks and the second was pale green with a conchoidal fracture and waxy lustre. Long, high-resolution XRD scans were performed on relatively thick powder specimens of both. The blue specimen produced no crystalline peaks whatever, while the green specimen produced a faint malachite pattern on a broad amorphous background. EDS showed copper and silicon to be the only heavy metal elements present and in variable amounts. 'Chrysocolla' has been reported from numerous localities in the Caldbeck Fells, but we are not aware of specimens that have been confirmed by XRD. Furthermore, the XRD patterns that are supposed to be characteristic of chrysocolla (published in the JCPDS index) are widely variable. Moreton (2007) investigated soft copper bearing gels from Tankardstown Mine, Co. Waterford in some detail and made comparisons with similar deposits from elsewhere and with material similar to the 'mineral' often called chrysocolla from the Caldbeck Fells. He concluded that these deposits are best referred to as 'copper-bearing silica gel'."
Habit:
(botryoidal) crusts and coatings; pseudomorphs after radiating sprays of malachite and as epimorphs after acicular cerussite
