The brightness and colour of a given mineral’s fluorescence depends on the impurities in the mineral. Those impurities are called “activators”. Different activators in the same mineral can cause different colours of fluorescence. Too much or too little activator in a normally fluorescent mineral can cause it not to fluoresce at all, or to fluoresce only dimly.
Therefore, it is not possible to use fluorescence to definitively identify minerals, but it can help confirm an identification. For example, if you are looking for a mineral in an area where it is known or likely to exist, and you find the expected colour of fluorescence under the correct wavelength, there is a high probability that you have found what you are looking for.
OPAL
WE SPECIALISE IN TORCHES FOR OPAL HUNTERS. If you are looking for opals you need a Long Wave (365nm) filtered torch.
The more powerful your torch, the more likely you are to find opals. Opal glows bright blueish-white under Long Wave (365nm) UV. Short (254nm) and Mid Wave (310nm) are of no use when hunting for opal because opal does not respond to them. 395nm and any unfiltered torches are also useless.
Our torches are being used by many opal hunters at Lightning Ridge, Coober Pedy, White Cliffs, Andamooka etc. Note that most Boulder Opal does not fluoresce and we do not recommend you get a UV torch for Boulder Opal hunting.
We recommend our FL2, FL8, FL8A, FL9, FL20 for Opal Hunting. The more powerful your torch, the more likely you are to find opals. FL20 and FL9 are our most powerful. FL20 has a narrow beam and will reach much further than all the others. FL9 has a wide beam which lights up a much greater area, but therefore doesn’t reach as far as FL20. FL9 is preferred by opal miners who have a mine. Some open cut miners have bought both FL9 and FL20.
NOTE: Opal fluorescence has nothing to do with the daylight colours of the opal. Opal fluoresces a bluish-white colour regardless of how the opal looks in sunlight. You shine the UV torch on the ground at night and if you see a bright blue-white spot you pick up an opal. UV does NOT affect or enhance the beautiful white-light colours of opal. UV will not make those colours brighter or more intense. Only white light will do that. UV light is for looking FOR opals, bright white light is for looking at them.
Recommended Torches: FL2, FL8, FL8A, FL9, FL20.
LITHIUM
Lithium occurs in spodumene, lepidolite, petalite, eucryptite. Spodumene is the most common and important of these. To find Spodumene you need a Long Wave UV source. It usually fluoresces orange/tan/pink under Long Wave UV light, 365nm being the optimal wavelength. It can fluoresce other colours (rarely), as can Lepidolite and Petalite. Eucryptite fluoresces a deep cherry red under Short Wave UV.
[Long wave UV is also known as UVA and Short wave UV is also known as UVC]
Several of our Long Wave 365nm torches are being used to find spodumene in Western Australia.
The video shows spodumene (18cm x 10cm) from a mine in WA fluorescing under an FL8 torch.
Initially the torch is about 3m from the rock, then about 2m and finally about 1m.
UPDATE: Fluorescence is much brighter under our new FL8A and FL20 365nm UV torches.
Recommended torches: FL8, FL8A, FL9, FL20.
SCHEELITE & POWELLITE
Scheelite is the ore for Tungsten. In its pure form it glows bright white/bluish-white under SW UV. To find scheelite you need a Short Wave UV source. Any of our Short Wave torches can be used. Several companies have bought our FS12, and have reported great results. Scheelite does not glow at all under LW or MW.
Scheelite and Powellite are closely related. Both can fluoresce under SW, but the color differs. Pure scheelite usually glows a bright bluish-white, while powellite typically glows creamy yellow. The fluorescence color of scheelite becomes more yellow as more molybdenum substitutes for tungsten in the crystal. So Scheelite can also fluoresce a yellowish colour.
Recommended Torches: FS8, FS12
RARE EARTHS
Quality UV torches are part of the toolbox of people searching for REEs (Rare Earth Elements). They can be used to find minerals that are known to contain, or to occur with, REEs. As well as the standard SW, MW and LW torches, other wavelengths such as 275nm and 340nm are useful because some REEs or REE-containing minerals may fluoresce most brightly under “non-standard” wavelengths.
Some REEs fluoresce, some don’t. Rare Earths can occur in other minerals where they may act as “activators” which cause fluorescence. So good UV torches in a variety of wavelengths can find associated fluorescent minerals such as fluorites, calcites, apatites etc which may contain REEs.
Recommended Torches: FL8A, FL20, FM8, FS8, FS12
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