Minerals of Scotland
STRONTIAN Calcite
& Fluorescent Calcite from Strontian. |
STRONTIAN Calcite
& Fluorescent Calcite from Strontian. Minerals & Fluorescence - A Quick Guide Strontian Links |
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FLUORESCENT MINERALS Fluorescence
in minerals can impress friends and non-mineral
orientated people alike. In the
past, fluorescence has been employed in prospecting for
scheelite, a tungsten ore, As for
rather nondescript specimens - such as those with
crystals difficult to distinguish clearly - The two
photographs below superbly demonstrate this. |
CALCITE - Bellsgrove
Mine, Strontian, Argyll, Scotland. |
Coroneted
CALCITE - Bellsgrove Mine, Strontian,
Argyll, Scotland. |
CALCITE from Strontian Calcite is found in
several forms... rhombic, "dog-tooth",
discoidal, flos-ferri... Though perhaps far
from being world-beaters, Crystals may also show a later crystal overgrowth of a differing habit from that of the earlier generation of crystals. Amongst the latter,
are the deep amber, interlocking, rhombic crystal groups
found in recent years. Some of these specimens display an
interesting internal light play. The specimens also fluoresce in Long Wave Ultra-Violet light. Additionally, amber calcite crystals may also have a partial peppering of tiny harmotome and/or brewsterite micro-crystals on their surface. |
CALCITE - Corrantee Mine, Strontian, Argyll. |
CALCITE
from Strontian. Left:
a scalenohedral crystal to 15mms with a final coating of
tiny hexagonal prismatic crystals (see above) |
CALCITE - Strontian, Argyll,
SCOTLAND. |
A secondary
overgrowth of hexagonal calcite crystals obscuring an
earlier growth phase of the "dog-tooth" habit. |
CALCITE - Whitesmith Mine, Strontian. |
CALCITE - Clashgorm Mine, Strontian, Argyll,
SCOTLAND. |
Fluorescence & Minerals |
| A Quick Guide | Some Fluorescent Mineral Examples | ||
| Fluorescence
occurs if a mineral emits visible light when illuminated
by a light source such as Ultra Violet. The Ultra Violet
spectrum is divided into Long Wave - The same mineral may fluoresce at one site, but not at another. Some respond to long wave but not short wave and vice versa. Some may respond to both. A few are
always fluorescent - and occasionally with a
characteristic colour. Scheelite, is the prime example,
responding always in short wave, ultra violet light The cause of
fluorescence is due either to lattice defects |
The
superb crystals and variety of colours of Weardale
fluorite has given the area a reputation among mineral
collectors throughout the world. The high level of fluorescence of fluorite from this classic area, adds an extra cachet other locations do not have. In Scotland, though not on the same level, but just as interesting, are the examples of fluorescent calcite from Wanlockhead (a rich pink colour in long-wave Ultra Violet light), anglesite from Leadhills, strontianite from the type locality, Strontian (both with yellow tones in Long-Wave) as well as calcite from Strontian. Studies on Weardale fluorite suggest traces of rare earth elements are an important factor in the fluorescent properties of fluorite from the area. Elements such as yttrium and europium have been cited (King; Dunham) as well as samarium and gadolinium (Bill/ Sierro & LaCroix). |
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the end
ACKNOWLEDGEMENT
This website wishes to thank David Green for giving permission to
publish the fluorescent calcite photographs.
Reference:
Rocks & Minerals, vol. 75, no.1. pp.54-61. "The Rogerley Mine, Weardale, England". (J. Fisher/ L. Greenbank).
© Minerals of Scotland - 2008.