Minerals
of Scotland |
Calcite & Fluorescent Calcite
from Strontian. |
Strontian - Minerals Strontian Main Page - Strontianite Calcite & Fluorescent Calcite from Strontian Strontian - Mines Clashgorm
Mine Section Main Site Scottish
Highlands External Links Strontium - ithe element and its properties - www.webelements.com Strontian - the village and its surrounding area - Strontian |
CALCITE - Corrantee Mine,
Strontian, Argyll. Though perhaps far from being world-beaters,
Strontian calcite can nonetheless make good specimens for
collectors. The mineral is found in several forms:
rhombic, "dog-tooth", discoidal, flos-ferri... 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 cause of the colouring of these calcites is unknown. These crystals may also have a partial peppering of tiny harmotome and/or brewsterite micro-crystals on their surface. Additionally, the specimens also fluoresce in Long Wave Ultra-Violet light. |
CALCITE from Strontian. left: a scalenohedral crystal to 15mms with a final coating of tiny hexagonal prismatic crystals (see above) from the Corrantee Mine. right: a "coronet" growth on the top rim of hexagonal prisms (as seen in the UV calcite photos above) from the Clashgorm Mine Section. |
CALCITE -
Strontian, Argyll, SCOTLAND. |
CALCITE - Clashgorm Mine,
Strontian, Argyll, SCOTLAND. |
CALCITE - Whitesmith Mine,
Strontian. |
A secondary overgrowth of hexagonal calcite
crystals obscuring an earlier growth phase of the
"dog-tooth" habit. |
Fluorescence & Minerals
CALCITE - Bellsgrove Mine,
Strontian, Argyll, Scotland.
Coroneted CALCITE - Bellsgrove Mine,
Strontian, Argyll, Scotland. |
Fluorescent Minerals Fluorescence in minerals can impress friends and non-mineral orientated people alike. A small display, or just showing one or two highly fluorescent examples, may astound them! In the past, fluorescence has been employed in prospecting for scheelite, a tungsten ore species, and the fluorescence of a mineral at a given site may be helpful for identification purposes. As for rather nondescript specimens - such as those with crystals difficult to distinguish clearly - these may be transformed, if the mineral has fluorescent properties. The two photographs above superbly demonstrate this. In normal lighting, the specimens are not particularly striking but, under ultra-violet light, they reveal a very clear and dramatic beauty. |
A Quick Guide 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 easiest source for the amateur collector to use, though with the potential drawback that fewer minerals respond to this light source; and Short Wave - which approaches X-rays in the light spectrum. The same mineral may fluoresce at one location, but not another. Some respond to long wave but not to 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 with a blue colour. Benitoite is a similar example. The cause of fluorescence is due either to lattice defects in the mineral and/ or the result of chemical impurities, which are known as activators. |
Some Examples The superb crystals and variety of colours of Northern England's 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 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). |
| 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. |