Albite.
Albite
has not been found in direct association with benitoite or neptunite.
It is common in minute veins in some of the surrounding rock, where it
is generally granular and determinable only by means of the microscope.
But in places it is developed in druses in the zone of mineralization
and appears as crystals δ to 10 mm. long growing from the blue-green
amphibole wall. These crystals are generally translucent grayish or
greenish in hue, due to included amphibole fibres.
Most
commonly the crystals are twinned according to the albite law. Simple
twins are the rule, but sometimes there are several very thin
polysynthetic lamellae intercalated between the two main halves of the
twin. The habit is defined by the dominance of
. The forms are named in order of size. Μ is the largest though never so large as to produce a distinctly tabular habit, Τ and ο about the same, and Ρ distinctly smallest. The general mode of growth is such that the crystals are attached
