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ILÍMAUSSAQ FLUORESCENCE
Historically, just
one variety of one mineral species from Ilímaussaq has attracted much
attention for its fluorescence: the translucent, gemmy red variety
of tugtupite.
Known largely to
jewelers and specialist mineral collectors, tugtupite is an odd
aluminosilicate of sodium and beryllium. It is uncommon elsewhere;
found at only two other places, and there only in small amounts.
But
here, at Ilímaussaq, tugtupite is relatively abundant—as grains,
small crystals, and even large masses to tens of centimeters across.
In the mid-1960s, Danish jewelers began marketing a newly discovered
translucent red variety of tugtupite as a semi-precious gemstone.
Exported, this has been mined locally for use in jewelry ever since,
making tugtupite more widely known, albeit in this single form.
Tugtupite,
however, occurs in many guises. It may be colorless, white, pale
pink, pinkish-red, red, violet-red or even pale blue. Its
fluorescence is also highly variable. In some tugtupite, different
fluorescent colors may be produced by applying different wavelengths
of UV.
The familiar gemmy variety is not always the most vivid—or
even the brightest—fluorescent tugtupite.
In terms of
fluorescent minerals, Ilímaussaq is home to much more than
tugtupite. For one, it’s also the ‘type’ locality for sodalite, a
rock-forming sodium aluminosilicate first discovered here in 1812.
Some other sodalite, notably from Ontario, Canada and Afghanistan,
has long been prized for its fluorescent and photochromic
qualities—the latter a variety sometimes termed ‘hackmanite’.
But we’ve found
the fluorescent sodalite from Ilímaussaq second to none in
brilliance—easily outshining specimens from other locations. It
emits an intense pumpkin-orange light under long- and midwave UV.
In
terms of the depth and speed of its color change, Ilímaussaq’s
photochromic ‘hackmanite’ sodalite rivals the best from Afghanistan
or the
Kola peninsula.
Additionally, a
number of other minerals which fluoresce occur here, including most
polylithionite, sorensenite, and beryllite, as well as some
analcime, chkalovite, feldspars, fluorite, and others.
Combinations of
sodalite, tugtupite (in myriad forms), chkalovite, polylithionite,
sodalite, beryllite, and sorensenite provide complex, world-class
fluorescent mineral specimens.
Ilímaussaq offers
the collector a peculiarly appealing fluorescent color palette and
an extraordinary range of textures. Recent improvements in UV lamp
technology, including more powerful shortwave sources with
high-quality filters, and the introduction of UV lamps which output
in “new” regions of ultraviolet, such as midwave UV, open up new
avenues for fluorescent exploration here as well. Ilímaussaq has
proven to be a remarkable fluorescent mineral locale, and this
exploratory collecting trip wonderfully successful.
(Another paper—describing
these minerals and their fluorescence in more detail—is
currently in preparation by the author.)
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