Fluorescent Color
BLUE
AMBER
A hydrocarbon Hardness 2-2 1/2
The fossil resin, amber, which is usually yellow but also reddish brownish or whitish in color, often fl blue-white, best LW.
BENITOITE
A silicate of barium and titanium Hardness 6-6
This unusual gem mineral is found in' only one locality, near the head waters of the San Benito River, California. The blue crystals normally occur associated with neptunite in natrolite, from which they are expose by acid etching. Benitoite fl bright blue SW.
CALCITE
Calcium carbonate Hardness 3
Calcite, the most varied of the fl minerals, has been found fl in almost every color of the rainbow. The blue fl calcites are usually ph. They appear to be sulfide activated. While red fl calcite is fairly common well crystallized form, blue fl calcite is usually found only in cleavable or granular masses.
The well known blue fl (SW) and ph calcite from the mercury mines Terlingua, Texas will usually fl pink LW, especially in those specimen having a pink daylight color. Masses of cleavable blue fl and ph (SW) calcite have been found at San Saba, Texas and nearby Marble Falls, interesting calcite from near Hurley, New Mexico fl a dull pink LW. When first exposed to SW radiation the reaction is pink, but over a few seconds duration the color turns violet. The ph is blue. It is the combination pink fl caused by electrons which rapidly return to their normal energy levels, with the blue ph caused by the slow returning electrons that causes the apparently purple fl. The calcite from Terlingua also illustrates this phenomenon.
A blue fl and ph calcite similar to the San Saba material has been found in Indiana.
CELESTITE
Strontium sulfate
Hardness 3-31/2
Many of the celestite crystals found in the sulfur mines of Sicily will fl a faint blue both LW and SW. These specimens are particularly showy where the fl celestite is implanted on an orange or pink (LW) fl calcite background. Both the celestite and the calcite usually have a brief greenish-white ph.
Fluorescent Color
BLUE
DIAMOND
Native carbon Hardness 10
Gem diamonds have been found which fl in a variety of colors including green, orange, red and blue, usually best LW. Blue is the most common fl color. Diamonds react well to the longest ultraviolet rays and even to the shorter wavelengths of visible light. The blue-white color of a fine diamond is often enhanced by its daylight fluorescence.
FLUORITE
Calcium fluoride Hardness 4
Historically, fluorite is the best known fl mineral. In fact, the word "fluorescence is derived from the name of the mineral fluorite in which the phenomenon of fluorescence was first noted and described. Blue is the most common fl color in fluorite. Intensity is usually best LW, diminished SW.
The outstanding localities for fl fluorite are the mines of Cumberland and Durham, England where outstanding groups of fl crystals have been found in quantity and variety. The natural color of these crystals is purple, green or yellow, with the best fl usually noted in the purple crystals. A portion of the daylight color of these specimens results from their fl in the LW ultraviolet present in ordinary white light. Most of these crystals are cubic in form and often consist of parallel growths of smaller crystals. There are a number of localities in the United States where blue fl fluorite has been found. Clear green masses have been found in Arizona, New Mexico and elsewhere. Large, clear green octahedral crystals have been found at Westmoreland, New Hampshire. Blue cubic crystals come
from New Mexico. In Ontario at Madoc transparent green cubo-octahedral crystals are found at many of the small fluorite mines which are worked from time to time. The fl of the Canadian material is not nearly so bright as that of the English fluorite. A bright green fluorite which fl a brilliant blue LW has been imported from South Africa on a trial basis for use as a steel making flux. Several tons of this attractive green material have found their way onto the specimen market.
HYDROZINCITE
A carbonate-hydroxide of zinc Hardness 2-21/2
Hydrozincite is a secondary zinc mineral common as thin fl coatings resulting from alteration of sphalerite, hemimorphite and smithsonite. It usually fl bright blue-white SW only. Hydrozincite is found associated with zincite and calcite on the old mine dumps at Franklin, New Jersey It is found associated with red fl calcite at Road Forks, New Mexico and Hurricane, Utah. It has been found in considerable quantity as earthy masses at Goodsprings, Nevada. Sometimes pockets in the earthy masses would be lined with tiny needle-like crystals of the fl hydrozincite
Elsewhere in the United States, hydrozincite has been found at Friedenville, Pennsylvania, Linden, Wisconsin, Marion County, Arkansas, Joplin Missouri, Cherokee County, Kansas, the Magdalena District, New Mexico and in the Tintic District, Utah.
Outstanding fl specimens of hydrozincite have come from Mapimi, Durango Mexico where brilliantly blue-white fl needle crystals of hydrozincite are associated with plattnerite and hemimorphite as cavity linings in limorite. This hydrozincite is unusual in that it not only fl blue-white SW but also a dull peach LW.
Further information on fl hydrozincite is given in the "Franklin" fluorescent section.
