jewel
has been set in the scepter of England and is now exhibited in the
Tower of London. The most noted diamond in the world is the Koh-i-noor,
found in India and presented to Queen Victoria. The Regent (137 carats)
like the Koh-i-noor, is an Indian diamond and was brought to England in
the 18th century. It is at present on exhibition in the Louvre, Paris.
Its association with the events of the most stirring and important period of French history, entitles it to considerable
historic interest in addition to its beauty as a gem. Other famous
diamonds are the Orlov, 193 carats, the Florentine, 133 carats, and
"The Star of the South" found in Brazil in 1853, 125 carats. Also
famous because of their color is the green Diamond of Dresden, 40
carats, and the blue "Hope" diamond from India, 44 carats.
Diamonds
of the first water, are colorless and free from flaws. There are many
faint shades of color, yellow the most common; rose, green or blue
shades are rare, especially blue. There is a black diamond called
carbonado, found in large masses.
Diamonds
are used commercially, as cutting tools, small fragments being used
for cutting and polishing gems and for cutting glass. Small pieces are
also utilized in the manufacture of engravers* tools. India, Brazil and
South Africa are the principal sources of Diamonds.
Diaspore: Hydrate
of Aluminium. This mineral occurs in orthor-hombic crystals, in
foliated masses, and sometimes stalactitic. Color whitish,
grayish-white, greenish-gray, yellowish; sometimes violet-blue in one
direction and reddish plum-blue in another direction, and pale
asparagus-green in another. Transparent to translucent. It is
infusible and receives its name from the fact that when exposed to a
flame, it decrepitates almost instantly and is dispersed. It is found
in Hungary, Norway, Switzerland and the Urals; also in Connecticut,
Massachusetts, North Carolina and Pennsylvania.
Diopside: A
variety of Pyroxene. Silica 55%, Lime 26-1/2. Magnesia 19%. Color
white, yellowish, grayish-white to pale green, and finally to dark
green. It occurs in prismatic crystals, also granular, columnar and
massive. Iron is present sometimes in small quantities.
Dioptase: Hydrous
Silicate of Copper. Silica 38.2%, Copper 50.4%. This is considered a
rare mineral. It occurs in rich emerald green crystals, having the form
of six-sided
prisms, terminated at each end by a three-sided prism, and is found
in Siberia, Russia, French Congo State, and in the copper mines of
Arizona.
