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 (1958) says: "sparingly associated with the pollucite which the author discovered at the Strickland Quarry in Portland in l954. It was in the form of glassy white or colorless cleavages and coarsely crystalline aggregates." Later, in Schooner (circa 1985), he elaborates: "Good specimens of white petalite, closely associated with colorless pollucite, were collected deep in the Strickland quarry, in the early 1950s. The author appears to have the only such material. It is usually granular, so the perfect cleavage is not as conspicuous as might be expected. The petalite was verified by X-ray diffraction. Similar petalite has been found on the dumps, intergrown with spodumene; the spodumene may be thoroughly altered to 'pinite', whereas the petalite, being much more stable, is in a fresh condition."
Habit:
granular to cleavable masses
Colour:
pale grey to white
Quality for species:
Poor for species, only of interest for locality collectors. (#)
Strickland Quarry, Strickland pegmatite, Collins Hill, Portland, Middlesex County, Connecticut, USA