Slide 2 — Outline

• What is fluorescence?
• What is ultraviolet light?
• Where is fluorescence used?
• What are fluorescent minerals?
• How do I collect them?
• Where do I collect them?
• Clubs and information
• Demonstration of fluorescence

Slide 3 — What is Fluorescence?

Fluorescence is the property of giving off light at one emission wavelength (color) when illuminated by light of a different excitation wavelength (color).

The excitation source can be a variety of wavelengths, including:

• Blue light
• Infrared light
• Ultraviolet light (typical)

The emission wavelength can also vary, but is always lower in energy than the excitation wavelength.

Phosphorescence occurs when energy absorbed by a substance is released slowly in the form of light.

This is used for “glow-in-the-dark” materials that are “charged” by exposure to light. Absorbed radiation may be re-emitted at a lower intensity for up to several hours.

Slide 4 — What is Fluorescence?

Fluorescence is a subatomic change of states. It occurs when a molecule, atom, or nanostructure relaxes to its ground state (lower energy) after being electrically excited.

Slide 5 — The Ultraviolet Spectrum

Slide 6 — What is Ultraviolet Light?

High-energy light at wavelengths outside the visible spectrum.

Types of ultraviolet light:

Long Wave (UVA)

• Present in sunlight
• Typical “black light” seen in discos, etc.

Slide 7 — What is Ultraviolet Light?

Short Wave (UVC)

• Not present in sunlight
• Most energetic
• Most fluorescent

Medium Wave (UVB)

• Present in sunlight
• Least fluorescent wavelength
• Used in DNA analysis

Slide 8 — Where Is Fluorescence Used?

• Fluorescent lighting
• White LED lights
• TVs (tube types)
• Germicidal applications
• Leak detection
• Erasing EEPROMs

Slide 9 — Where Is Fluorescence Used?

• Curing epoxy, paint, etc.
• Readmission control
• Laundry detergent
• Forensic investigation
• Medicine—cellular imaging, DNA analysis, etc.
• Counterfeit currency detection
• Gem and mineral prospecting for various minerals, e.g., scheelite (an ore of tungsten) and opal
• “Noodling” for opal
• Collecting and display cases

Slide 10 — UV Lamps: Lamp Uses

Permanent (Display)

• Large
• Require lots of power
• Can produce large amounts of UV light
• Main use in display cases, discos, etc.

Prospecting (Portable)

• Small
• Portable
• Lightweight
• Designed for prospecting “in the bush”

Slide 11 — UV Lamps: Lamp Types

Fluorescent Tubes

By far the most common.

Advantages

• Powerful
• Available at short, medium, and long wavelengths

Disadvantages

• Bulky
• High power use
• Expensive

UV LED Flashlights

Advantages

• Lightweight
• Inexpensive

Disadvantages

• Lower power
• Limited availability at shorter wavelengths at a reasonable price

However, they are becoming more powerful and less expensive.

Slide 12 — Build Your Own Portable UV Lamp

• A cheaper option for portable lamps
• Most expensive component: Hoya U-325C filter
• Short-wave UV bulb: can use a germicidal lamp
• Long-wave UV bulb: available from a number of manufacturers
• Plans: see Fluorescent Mineral Yahoo Group
• Requires an electronic ballast
• Requires a large battery carried in a backpack
• CLF spotlight case
• Reflector can be important

Slide 13 — Homemade Portable UV Lamp: Version 1

Slide 14 — Homemade Portable UV Lamp: Version 2

Slide 15 — Homemade Portable UV Lamp: Version 3

Most inexpensive option: 12-volt portable CFL lamp, Bayco SL-912T

Almost everything is already included:

• Replace lights with UV bulbs
• Remove plastic cover and glue filter onto the cover
• Contains its own electronic ballast

Disadvantage: Reflector is non-optimal.

Slide 16 — Display Cabinets

Usually a homemade affair.

• Lamps mounted on top and hidden from view
• Constructed to vent heat
• Glass or plastic (Lexan) can be used to shield viewers from ultraviolet light
• Lexan is best
• Prevents UV from lighting up the surroundings and distracting from the specimens
• Glass will have a glowing side and a non-glowing side—make sure the glowing side is on the outside
• Line the inside with black felt
• Can use short-wave, long-wave, or both

Slide 17 — Typical Minerals That Fluoresce

• Willemite
• Fluorite
• Sodalite
• Wernerite
• Calcite
• Opal
• Scheelite

Minerals may react differently to long-wave and short-wave UV:

• Different intensities
• Different colors

Short-wave fluorescence is usually more energetic.

Slide 18 — Different Responses to Different Wavelengths

Photo by HP Garland, FMS

Slide 19 — Where Can I Get Fluorescent Minerals?

• Buy on eBay
• Buy at gem and mineral shows
• Trade with other collectors
• Collect your own

To find shows near you, go to:

Slide 20 — Where Can I Collect Fluorescent Minerals?

Many areas contain local fluorescent minerals, but some of the more famous locations include:

• Franklin, New Jersey
• Mont Saint-Hilaire, Quebec, Canada
• Arizona, Nevada, and California
• Purple Passion Mine, Wickenburg, Arizona
• Virgin Valley, Nevada
• The Ilímaussaq Complex, South Greenland

Slide 21 — Franklin, New Jersey

The location of a large, complex zinc deposit that has been mined since the 18th century. It contains some of the most complex silicates in the world.

The mines are now closed, but there are plenty of dumps for digging.

Its unique chemistry has made some of its minerals among the most fluorescent in the world.

• Willemite
• Calcite
• Hardystonite
• Etc.

Many minerals found here occur nowhere else in the world.

Slide 22 — Typical Franklin Fluorescent Minerals

• Nice four-color combination: willemite, calcite, clinohedrite, and hardystonite
• Calcite and willemite
• Willemite and calcite

Slide 23 — Mont Saint-Hilaire, Quebec, Canada

• Alkaline intrusion complex—geologically very rare
• Over 51 fluorescent minerals found at this location
• Sodalite, albite, apatite, polylithionite, etc.
• Polylithionite and albite under SW
• Genthelvite crystals under SW

Slide 24 — Arizona, California & Nevada

• Willemite, calcite, fluorite, and aragonite from the Purple Passion Mine, Wickenburg, Arizona
• Common opal from Virgin Valley, Nevada

Slide 25 — The Ilímaussaq Complex

The Ilímaussaq Complex is a unique geological intrusion in an area of southern Greenland that is free of ice.

• Near the town of Narsaq
• The Tunulliarfik and Kangerluarsuk Fjords cut through the middle of the Ilímaussaq Complex
• Some of the most unusual minerals in the world can be found here
• Gem-quality ussingite
• Massive veins of sodalite, including tenebrescent green sodalite
• Brilliant assortments of multicolor tugtupite
• Deeply tenebrescent green sodalite

Slide 26 — The Ilímaussaq Complex

Slide 27 — Greenland Fluorescent Minerals

• Yellow sodalite
• Tugtupite
• Analcime

Slide 28 — Opals and Fluorescence: Australian Opal

• Most Australian opal fluoresces better under long-wave than short-wave UV
• Most boulder opal does not fluoresce
• Some Lightning Ridge opal fluoresces white
• Some Andamooka opal and opal matrix fluoresce white
• Most Coober Pedy opal fluoresces white
• Most Mintabie opal fluoresces white
• Most Lambina opal fluoresces white

Slide 29 — Opals and Fluorescence: American Opal

• Most American opal fluoresces bright green
• Tecopa opal fluoresces more strongly under short-wave UV
• Hyalite opal is among the brightest fluorescent minerals
• Virgin Valley common opal is very bright and has high concentrations of uranium
• Precious opal does not fluoresce
• Wyoming common opal fluoresces bright green and orange
• Spencer opal has a weak white response to SW and LW
• Ice Cream opal has a strong green response to SW and LW

Slide 30 — Other Opal

• Ethiopian opal does not fluoresce
• Brazilian opal: some mild LW fluorescence; some strong green SW fluorescence
• Peruvian opal: ?
• Whitesail opal: no fluorescence
• Mexican opal: no fluorescence

Slide 31 — What Causes Minerals to Fluoresce?

Pure minerals usually do not fluoresce.

Exceptions:

• Scheelite
• Powellite
• Cerussite

Activators: Trace elements that enable fluorescence.

• Manganese
• Lead
• Uranium
• Rare-earth elements, especially europium

Quenchers: Their presence can stop fluorescence.

• Cobalt
• Nickel
• To a lesser extent, copper

Slide 32 — A Word on Safety…

Ultraviolet light can be dangerous.

• Long-wave UV is safe (e.g., black lights in discos)
• Medium-wave and short-wave ultraviolet light can burn the skin and eyes and increase the risk of skin cancer
• Damage is based on exposure time
• ALWAYS use eye and skin protection with medium- and short-wave ultraviolet light
• Short-wave ultraviolet is almost completely stopped by most forms of glass or plastic
• ALWAYS avoid staring directly into a UV light source

Slide 33 — UV Demonstration

If you wish to participate, please wear the glasses or plastic frames provided and do not stare directly into the UV light.

Various minerals are on display:

Opal from Australia and America

Franklin calcite and willemite

• Bright red and very bright green under SW

Tugtupite from Greenland

• Orange under LW and red under SW
• Exhibits tenebrescence—the ability of UV to semi-permanently change the actual color of the mineral

Wernerite from Canada

• Bright yellow under LW

Miscellaneous specimens

Slide 34 — The End

Slide 35 — Backup Slides

Slide 36 — Germicidal Low-Pressure Mercury Lamp Spectrum

• Most of the energy is at 254 nm, in the middle of the UVC band
• Some additional energy is in the UVA and violet spectrum
• Requires a visible-blocking filter to block violet light, which would otherwise overshadow the fluorescence

Slide 37 — Ultraviolet-Transmitting, Visible-Absorbing Filter

Hoya U-325C Filter

• Spectrum cuts off visible light
• Expensive: $170 for a 6″ × 6″ glass plate
• Can be cut in half for two lamps
• Limited lifespan due to “solarization”

Slide 38 — Germicidal Low-Pressure Mercury Lamps

• Designed to kill microbes in AC systems, wands, etc.
• Germicidal—kills bacteria, viruses, dust mites, etc.
• Clear, with no phosphors
• Made of quartz, not glass

Slide 39 — UV Lamps: Where to Get Them?

Purchase New

Retail brands—most carry portable and display lamps:

• Superbright II
• Way Too Cool Lamps
• Ultraviolet Lighting Products
• “Ultralight 2002”
• LED lamps
• Spectroline
• Cole Parmer

“I added a ‘Woods Glass’ filter to black out the visible light. Photo stores carry them.”

Purchase Used

• eBay
• Internet auctions
• Surprisingly inexpensive surplus scientific equipment
• Large display lamps
• Transilluminators used for DNA research
• Can often salvage the filter from them
• Usually medium-wave
• Gem and mineral shows
• Want ads

Slide 40 — Clubs & Information

• Fluorescence Mineral Society
  • Worldwide organization
  • Large local Southern California chapter
• Fluorescent Mineral Yahoo! Group—online blog
• American Opal Society

Recommended Books

The World of Fluorescent Minerals — Stuart Schneider

Collecting Fluorescent Minerals — Stuart Schneider

Originally posted on Nature’s Rainbows.