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!
Was recorded as Limonite. The identity of goethite as the species is visually quite obvious. The mineral occurs in two major modes. The main interest in goethite here is the black mammillary masses. Very nice cabinet display pieces were relatively common half a century ago (1960's) but are hard to come by now. The other mode is brown cellular cavity-ridden pseudomorphs after siderite retaining some of the rhombic orientation in the walls of cavities. The interest here is finding nice malachite crystals in the vugs. Furthermore, nice rhombic pseudomorphs of goethite after siderite crystals are somewhat common. A lot of the quartz at the mine has drusy crystal surfaces richly impregnated by goethite, making attractive sparkly brown pieces.
Quality for species:
Good crystals or rich for species - important (!)
Significance:
Unusual or interesting association, relationships with other species, pseudomorphism etc. - see notes.
Conrad Hill Mine, Cid Mining District, Davidson County, North Carolina, USA