Willemite, calcite - Franklin, NJ

Description

A beginner's specimen of willemite and calcite. Here we have a moderately coarse mass of semi-translucent to opaque, white calcite. Scattered throughout the matrix are pale green, glassy, semi-translucent grains of willemite. Associated are grains of black, metallic franklinite.
Willemite is a zinc silicate, and it was named after King Willem of the Netherlands from the locality at the Moresnet (Plombières-Altenberg-Moresnet) mining district, Verviers, Liège Province, Belgium. This species was previously discovered in 1825 and was identified as "siliceous oxyde of zinc" by Lardner Vanuxem and William Hypolitus Keating. At the time, "siliceous oxyde of zinc" was a synonym of electric calamine, now known as hemimorphite.
Franklinite is a complex zinc manganese oxide, and it was named in 1819 by Pierre Berthier for the type locality of Franklin Furnace (now Franklin Borough), New Jersey. Silliman (1920) translated Berthier's article: "As the chemical nomenclature cannot in every instance furnish a name, I propose to give it that of The Franklinite, in order to remind us that it was found, for the first time, in a place to which the Americans have given the name of a great man, whose name is equally venerated in Europe as in the new world by all the friends of science an humanity." and this would be Benjamin Franklin. Franklinite is a member of the spinel group, the only one of three spinel family members to have zinc, gahnite, and zincochromite being the others. This species has been reported and observed in many world localities, though nowhere else in minable quantities.
The willemite fluoresces a bright green and the calcite a bright red under shortwave (254nm) ultraviolet light. This is a good beginner's specimen.
Dimensions are
8.1x6.3x5.2cm - 3¼x2½x2in.
Please note the centimeter cube and inch bar for scale.
Weight in grams and ounces:
222.4g - 7.85oz.
From the Franklin mine, Franklin, NJ.
The previous collection this specimen was is #52, Mark Boyer.
#52 is the museum's Collection Sale number previously offered in the museum shop.
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All potential buyers need to be aware that being able to view fluorescent minerals requires an ultraviolet lamp. Most of the minerals from the Franklin and Sterling Hill zinc mining district fluoresce under
shortwave ultraviolet light
.
The shortwave wavelength is
254nm
or otherwise known as
UV C
. Always read the description carefully to determine if the main mineral of interest for a particular specimen will fluoresce.
ALL
fluorescent minerals depicted in our storefront are illuminated by two (2) 9 watt Triple short/mid/longwave AC Model 9SM-110 Way Too Cool LLC ultraviolet lamps, and the shortwave tubes and filters were replaced in late 2018.
There are several available brands and models of ultraviolet lights on eBay and other online sources. For further information on ultraviolet light and fluorescent minerals, copy and paste the following and go to >>>
geology.com/articles/fluorescent-minerals
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DISCLAIMER: Every reasonable effort was made to identify the mineral species noted in each specimen accurately. The occasional label from previous collection(s) may misidentify some species, and the current title and description here reflect the latest mineral species identification.
A modest effort was made to depict a fluorescent specimen accurately as possible.
In some cases, overexposure should be expected in select photographs to compensate for a fluorescent specimen's weak response.
All buyers should exercise safe viewing practices regarding the use of ultraviolet light. Visual dark adaption is highly recommended in the optimal viewing of fluorescent minerals. Buyers should also be aware of what type of lighting to view the specimens under. This can result in perceived differences of color and contrast due to color and contrast shifting under various kinds of lights available.
All photographs were taken with a Nikon D5300 digital camera with a Nikon DX AF-S 18-55mm lens attached with a UV filter. Lighting was done with a pair of OSRAM 8.5 watt LED A19 5000K 800 lumens bulbs in brushed aluminum reflectors. The photographs were processed on a color-calibrated flat panel monitor. Do note the Imperial measurement conversion is the nearest equivalent to the listed metric measurement.
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