Gummite: An
alteration product of Uraninite—composition doubtful. It occurs in
crystalline form and in rounded and flattened pieces looking like gum.
Color is reddish-yellow to orange or hyacinth-red; feebly translucent.
It occurs in pitchblende at Joachimsthal, and is abundant at the Flat
Rock mine, in Mitchel County, North Carolina, and also in other
localities with Uraninite, a source of radium salts. (See Radium.)
Gypsum: Hydrous Calcium Sulphate. Sulphur 46.6%, Lime 32.5%. This
mineral, the most important of the hydrous sulphates, occurs in masses
associated with limestone, in crystals, fibrous, and in granular
aggregates. It is white, colorless and transparent when pure; gray,
red, yellow, blue or black when impure. The crystallized transparent
variety is called Selenite, some of the crystals containing a so-called
"bubble" Crude Gypsum is used in the manufacture of plaster, as a
retarder in Portland cement, and as a fertilizer. Small quantities are
used in glass manufacture; also as a whitewash; as a deodorizer; and as
an adulterant in candy and other foods. It is sometimes used as a
medium of sculpture. A white massive variety, known as Alabaster, is
used for carving ornaments, and lamps.
After
the United States, France is the largest producer of gypsum. Burnt
gypsum is called "Plaster of Paris," because the Mont-martre gypsum
quarries are near Paris, and are famous for supplying it.
Halite: Sodium
Chloride. Common or rock salt. This mineral occurs in cubes and
crystals, also as massive and granular, is white or colorless; also
yellow, reddish, bluish and purplish. It is the best known and most
abundant native chloride, is soluble and the taste, saline. Salt is
used for the preservation of organic substances, is employed in glazing
pottery, in metallurgical processes, for clearing oleomargarine, in
making butter and in the more familiar household operations.
Halite
is the chief source of sodium compounds and is found in large
quantities at Saginaw, Michigan; also in New York, California, Utah,
Kansas, Missouri and many places in Europe, especially at Stassfurt,
Germany.
Harmotome: Barium
Compound. Occurs in crystals, and forms complex groups of twins. Color,
white, gray, yellow, red or brown. It is found at Strontian,
Scotland, in fine crystals some an inch thick; also at Norway,
Silesia, and in the Harz Mountains. In the United States, small
crystals were found while excavating the Fourth Avenue tunnel in New
York City. They are also found on the north shore of Lake Superior.
Thirty-two
