Calcium tungstate                                                                                                              Hardness 41/2

This important ore of tungsten is heavy, usually white, cream or gray in color, and is normally very difficult to distinguish from other minerals in the rock. However, its marked SW fl and non-fl LW make it very easy to locate and identify with ultraviolet. In fact, ultraviolet prospecting is practically the only way that scheelite is located. During World War II when tungsten was in great demand and short supply, a great deal of successful ultraviolet prospecting took place in the western United States. In some of the Canadian gold mines the rock was checked after each blast and any scheelite ore was set aside. Scheelite has been mined in many areas of California, Nevada, New Mexico and Idaho. The dump from practically any of the tungsten mines will produce fl specimens

Large masses of scheelite are not common. Well formed crystals are highly prized.

In the east, scheelite has been mined in Trumbull, Connecticut and also in South Carolina, but the bulk of the commercial development has been in the western states.


Fluorescent Color

ORANGE, YELLOW, GOLD

Lead sulfate                                                                                                                             Hardness 3

Anglesite often occurs i« well developed crystals which fl yellow. It is found in lead mines in many countries associated with cerussite and galena.


Barium sulfate                                                                                                               Hardness 3-31/2.

Most barites which fl react with a white or cream color, usually best LW. Hot Springs, North Carolina, however, has produced an unusual barite which fl a bright golden orange. This material is gray colored in daylight and fl in thin veinlets of bright color. Occasionally bright fl bands have been found an inch or so in width.


Calcium carbonate                                                                                                                   hardness 3

Calcite which fl orange has been found in the quarries at Crestmore, California. A sulfide vein at Lowville, New York has produced a calcite which fl bright orange in association with a more common red fl calcite and blue fl fluorite. Drusy crystal coatings and stalagtitic masses which fl in beautiful shades of orange, cream and pink are found in the sulfur mines of Sicily. Pale yellow fl calcite is found in several localities including crystal specimens at Bound Brook, New Jersey and cleavable masses at Marble Falls, Texas.

Caliche, a carbonate coating often found on the surface of desert stones, will often show an orange fl SW.


Lead carbonate                                                                                                               Hardness 3-31/2

Found in many lead deposits. Commonly fl yellow LW and also in X rays.


Basic fluosilicates of magnesium                                                                                   Hardness 6-61/2

The two minerals, norbergite and chondrodite, are similar in composition, appearance and fl and are not easily distinguished from one another. They often occur together at the same localities and are sometimes intergrown. The daylight color of these minerals ranges from white through a hyacinth red with the most common color being tan or honey-yellow. The fl ranges from bright golden yellow or yellow-orange to buff (SW) and is Fluorescent Color, usually brightest in the lighter colored specimens. Fl LW is slight. Fl chondrodite is found as scattered grains and crystals in the limestones of northern New Jersey at Sparta, Ogdensburg and Franklin. A similar occurrence in limestone is at Newcomb, New York.


A carbon-hydrogen compound, probably C24H18,g                                           Hardness less than 2

The hydrocarbon curtisite has been found in the Hot Springs area of Skaggs Springs, Sonoma, California. Hydrocarbon infusions in travertine from the Clear Lake area of California have produced specimens with fantastic patterns, which fl white, cream and pale green in swirls, bands, spots and flamelike growths.


Carbon                                                                                                                                   Hardness 10

Diamonds have been found which fl yellow and orange. See diamond in the "blue" section.


A complex silicate of sodium and aluminum                                                               Hardness 51/2-6

containing chlorine and sulfur One of the most interesting of all fl minerals is hackmanite, which is found near Bancroft, Ontario. It has also been reported from West Greenland, Kishengahr state, Rajputana, India and the Kola Peninsula, Lapland. Hackmanite commonly fl bright apricot LW and shows a similar but less brilliant fl SW.

When a block of nepheline containing hackmanite is first broken open the hackmanite will be easily distinguished by its brilliant raspberry red color. The color disappears with a few minutes exposure to daylight or artificial light. It can, however, be returned to its brilliant color by a few minutes exposure to SW ultraviolet. It will retain the bright raspberry red color as long as it is kept in the dark. On exposure to light it will once again fade. This color reversal can be repeated indefinitely. The property of reversing color with changes in light radiation has been called "reversible photosensitivity". More recently it has been called "tenebrescence