needles,
by hand and machinery. The working of coral is carried on in
Marseilles, Leghorn and Genoa. The coral is exported to India, Persia,
China and Japan. Coral may also be used for cameo.
Amber
Amber
is an inorganic product or fossil resin, occurring in the form of
pebbles or irregular shaped masses in beds of Tertiary age. The life of
its period could be studied by the insects entombed in the amber. The
amber was first in a sticky state, when the insects were entrapped in
it. It was exuded by an extinct genus of pine tree, known as Pinvs succinifera. Most
of the world's amber comes from the deposits along the southern shores
of the Baltic Sea, West and North of Konigsberg, Germany. But amber
occurs also in Rumania, Sicily and Burma.
Baltic
amber occurs in grains and lumps weighing even up to 20 lbs. It
contains inclusions of a great variety of insects and plant remains,
which are well preserved and are objects of scientific and popular
interest. Minute inclusions of pyrite may also be present. Hardness = 2
to
2-1/2. Amorphous. Fracture: conchoidal, and takes a good polish. Specific gravity 1.0 to 1.1. It floats in a glass of
water
containing four heaped tea-spoonfuls of salt. Colour: yellow, but other
colours as brown, white, red, etc. may also be present. Lustre: greasy.
Clear and transparent or cloudy to translucent and opaque. Amorphous,
isotropic. Refractive index = 1.54. It is easily electrified by rubbing
with a cloth and will attract bits of paper. It is warm to the touch
being a very poor conductor of heat. It is a good insulator and is used
in electric and radio apparatus.
Compositions—It is a mixture of several resins, succinic acid and a volatile oil called amber oil with also a little H2S.
Occurrence,—The
Baltic Sea coast exposure is the most important. Palmnicken is the
centre of mining operations. The manufacturing works for amber articles
are at
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