The sodium-rich end-member of the plagioclase feldspar group, called albite, from the Latin albus, because of its whitish color, may look similar in appearance to adularia moonstone it cut en cabochon. Furthermore, in both cases, the composition is midway between that of orthoclaso and that of albite: albite moonstone can, in fact, be defined as a microperthitic association of albite and orthoclase with a
predominance of albite. For this reason, it is considered acceptable to use a similar name for the two gems.
Appearance It is typically misty, semitransparent or semiopaque with a pale, shimmering reflection, less well defined than in chatoyant stones. It may be milky white in color. or dull yellow, yellow-gray or greenish gray. It is almost always cut en cabochon. Curved pieces are also cut as necklace beads or pendants.
Distinctive features The adularescence is quite distinctive. This is also found in adularia moonstone, but the two are distinguishable by their density. which is higher (from about 2.62 to 2.65 g/cm3 in albite moonstone. The refractive indices. which are always hard to establish in curved stones, are slightly higher (rm 1.525, ny 1.536) than those of orthoclase, with slightly stronger birefringence as well. The yellowish or light brown coloration of some specimens also distinguishes it from adularia moonstone.
Occurrence It comes mainly from Canada and Kenya but occurs also in India and Sri Lanka. In the latter two countries, however, it is confused with the similar variety of orthoclase.
Value Somewhat low, like adularla moonstone.
Slmulante and synthetics It is imitated by milky synthetic spinel_ which, however, (virtually) lacks the mobile reflection. It is not manufactured synthetically.