Strontian - Minerals

Strontian Main Page - Strontianite

Brewsterite & Harmotome

Strontian's Other Minerals

Calcite & Fluorescent Calcite from Strontian

Strontian - Mines

Clashgorm Mine Section
Corrantee Mine
Fee Donald Mine
Whitesmith Mine - Intro
Bellsgrove Mine

Main Site

Site Links
Home

Scottish Highlands
Grampian Highlands
Isle of Skye

External Links

Strontium - ithe element and its properties - www.webelements.com

Strontian - the village and its surrounding area - Strontian

CALCITE - Corrantee Mine, Strontian, Argyll.
Sub-parallel, hexagonal prisms with curved pinacoid overgrowing an earlier calcite crystal, 1 cm. in size, of a different habit.

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...
It occurs with all the other species found at the locality. 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 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.

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.

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.

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).