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Fluorescent Minerals
by Mark Isaacs

Fluorescent minerals are natural; they are not painted or artifically treated in any way. Of over 3600 known mineral species only about 500 are know to fluoresce. There is no way to know by looking at a rock under regular, visible light whether it will fluoresce under ultraviolet.

Invisible ultraviolet light coming from lamps in the display cases causes electrons within the mineral molecule to jump to a higher energy level. As the electrons fall back to their normal energy level they give off the extra energy in the form of visible light which appears to our eyes as many different colors. Some minerals will fluoresce only one color while others may fluoresce different color (or not fluoresce at all) depending on the presence of minute amounts of different "activators".

Most minerals do not fluoresce, and there is no way to know by looking at a rock under regular light whether it will fluoresce. Fluorescence is not the same thing as radioactiviity. Some radioactive minerals fluoresce, and some do not.

Ultraviolet light has a range of wavelengths, and some minerals will fluoresce under one wavelength but not another. Interestingly, some minerals will change color when viewed under different wavelengths of ultraviolet. "Long wave" (LW) ultraviolet with a wavelength of 366nm is the same as the UV coming from blacklights like those in hardware stores and dance clubs. It is relatively harmless. "Short wave" (SW) UV at 254nm, however, can cause burns on exposed skin and eyes. Most fluorescent minerals are sensitive to short wave (SW) UV while only about 15% are sensitive to LW, and for that reason most of the lights in the display cases are SW. Special glass and plastic are used on the front of the cases to block SW UV from being transmitted, making displays safe to view.

Mark Isaacs is Northern California's Regional Vice-President of the Fluorescent Mineral Society and past guest speaker at our general education meeting.

Additional Information on Fluorescent Minerals
Fluorescent Mineral Society

Look for "Way Too Cool" brand fluorescent lighting - I could not find a direct website, however several places sell them.

Highly Recommended Books
Some are out of print but you can find them through used book dealers (on amazon) or libraries.

Fluorescence, Gems and Minerals Under Ultraviolet Light
by Manuel Robbins
"Fluorescence" documents all major locations where fluorescent minerals are found, listing geographic boundaries and the known minerals in each area. Entire chapters are devoted to several key fluorescent minerals including sphalerite, scheelite, Terlingua calcite and fluorite. Data tables list all mineral activators, as well as the minerals in which they produce fluorescence. A comprehensive catalog of known fluorescent minerals provides fluorescent characteristics, including an extensive description of color variations in a quick-reference format.

The Collector's Book of Fluorescent Minerals
by Manuel Robbins
The Collector's Book of Fluorescent Minerals ends the search for technical data by identifying minerals that fluoresce, and answering a wide range of questions about what makes them fluoresce and where they can be found. It also gives basic guidance on starting collections, building up collections, and preparing collections for display.

Nature's Hidden Rainbows, Fluorescent Minerals of Franklin, New Jersey
by Robert W. Jones, Jr.
Bob was one of the first fluorescent mineral hobbyist to write a regular column in Rocks and Minerals magazine entitled "Collecting Fluorescent Minerals" and currently the Senior Consulting Editor for Rock and Gem magazine. The book contains information on the history and mineralogy of the Franklin and Sterling Hill orebodies. Also included are some great historic pictures of the area, as well as color photographs of some of the fluorescent mineral specimens.

The Minerals of Franklin and Sterling Hill, a Check List
by Clifford Frondel
Dr. Clifford Frondel, was a professor of Mineralogy at Harvard University and devotes the first two sections of the book to a general background of the Franklin area, including mining history, famous collections and geology. The third section contains an alphabetical check list of mineral species, characterizing each by its manner of occurrence, chemical composition, relative abundance and mineralogical history. The final section of the book contains a complete list of references which was current at the time of publication. The book also contains quite a few black and white photographs of fantastic specimens.

The Story of Fluorescence
by Raytech Industries, Inc.
Published in 1965, this booklet was once provided free with every purchase of a Raytech ultraviolet lamp. Written in easy to understand language, ideal for kids and those who are new to the hobby. The booklet also includes some fun and educating experiments for kids, and describes some practical applications for fluorescence, other than mineral luminescence.

World of Fluorescent Minerals
by Stuart Schneider
Beautiful colored photographs showing minerals under normal as well as under UV lighting. Nearly a thousand color photos with descriptions and geological information.

Last Updated: 4/8/24
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