CAESIUM BERYL.
A
colorless to bluish-white or pinkish-white variety of beryl containing
a small percentage (1.60 per cent to 3.6 per cent) of oxide of caesium
was first discovered in Hebron, Oxford Count}', but has since been
found to occur at a number of other pegmatite localities in the western
part of the State, notably at Mount Mica in Paris, at the Dudley farm
in Buckfield, Oxford County, and at the feldspar quarry of Mr. A. R.
Berry in Poland, Androscoggin County. Generally it occurs in somewhat
irregular masses in the solid pegmatite, but in some occurrences shows
regular crystal forms. When cut it makes a stone of high brilliancy
which as a night stone is considered by some to he superior to many
diamonds. It is valued chiefly because of its resemblance to the
diamond. Flawless cut stones of moderate sizes sell at retail at
present at from So to 820 a carat.
TOPAZ.
Topaz is a silicate of alumina containing fluorine and having about the composition AlnSi)i(.):,-F1,).
It may be colorless, straw yellow, or wine yellow, or may show laint
tints of gray, green, blue, or red. Its hardness is S, and it is thus
capable of scratching quartz. It is also much heavier than quartz,
having a specific gravity of 3.4 to 3.65. The mineral belongs to the
orthorhombic system and its crystals are usually prismatic in form,
with one end terminated by crystal faces. It possesses a perfect
cleavage at right angles to the prism axis. Transparent smoky quartz is
frequently called smoky topaz, and the so-called Spanish topaz is
simply smoky quartz heated until it assumes a yellow color. Clear,
colorless quartz is also sometimes sold under the name of topaz.
So
far as known to the writer, topaz in any considerable amounts has been
found in Maine only at Harndon Hill in Stoneham, Oxford County. (.See
p. 100.J
