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!
Meikle (1989): Native silver is rare, although it formed with some local abundance on, and partly in, pale yellow, translucent prehnite. In addition, it may also extend across, or into, small (<15 mm) cavities in the prehnite. Even more rarely it occurs within, or on, adjacent calcite. The base of the prehnite is generally opaque and whitish in colour, and frequently is distinctly banded parallel to the surface by malachite staining developed from a thin brownish-green copper-impregnated layer within the prehnite. Occasionally well-crystallized native copper is found on the prehnite. The native silver is also well-crystallized, and is generally very bright and lustrous but with an iridescent tarnish developing upon exposure. The crystals, though small, exhibit a variety of forms, from the simple or modified single (<0.15 mm) and twinned (0.35 x 0.25 x 0.15 mm) cubes, to elongated symmetrical or unequal bi-pyramidal forms of square, or nearly square, section (<0.4 x 1 mm). The latter are frequently extended at one end into filiform silver (<1.25 mm). More commonly, however, the elongated crystals, <9 mm long, are approximately square in section (<0.14 mm). One specimen was observed with 12 sides, tapering in thickness from 0.15 to 0.06 mm, while a second forms a complex cruciform twin. Other unusual forms are complex and appear to be 13 multiple crystals in parallel growth from a common base; one such specimen is 3.4 x 0.4 x 0.1 mm. Upwards of 50 individual crystals have been recovered from a relatively small volume of rock. The reference above to 'local abundance' is illustrated by one specimen, measuring 30 x 40 x 20 mm in size, carrying 12 individual crystals."
