Margarosanite, prehnite - Franklin, NJ

Description

A s rich specimen of margarosanite and prehnite. This is a thumbnail-sized specimen, yet it is rich in two fluorescent species, margarosanite and prehnite. This would be considered an all-around specimen. Franklin is the type locality for margarosanite and was named in 1916 by William Ebenezer Ford and Walter Minor Bradley from the Greek for "pearl" and "tablet," in allusion to the pearly luster and lamellar structure of the crystallized material. The original specimens were found in 1898, but the mineral remained unnamed for nearly 18 years. Here the margarosanite, a lead calcium manganese silicate, is a massive pale pink with translucent sections, and there are a few pearly white platy spots scattered here and there. The margarosanite fluoresces an astoundingly bright blue-white under shortwave (254nm) ultraviolet light.
Associated with the margarosanite is prehnite. The prehnite from Franklin is totally unlike most world occurrences of prehnite, renowned for the globular masses of bright green. Here the Franklinite prehnite, a calcium aluminosilicate hydroxide, is pearly white masses scattered in the matrix as sections and spots and intermixed with the margarosanite. The prehnite fluoresces an orange-pink hence a "peach" color under shortwave (254nm) ultraviolet light. The remainder of the specimen is taken up by sections and grains of vitreous, orange-brown garnet.
No fluorescent collection of Franklin and Sterling Hill is considered complete until there is a rich example of a margarosanite in it. This specimen will help fill that niche in any collection.
Dimensions are
2.7x1.6x1.5cm - 1x½x½in.
Please note the centimeter cube and inch bar for scale.
Weight in grams and ounces:
4.7g - 0.17oz.
From the
Franklin mine, Franklin, NJ.
The previous collection this specimen was in is #157, James Van Tassel.
#157 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.
--- All photographs appearing on this listing or any other Franklin Mineral Museum listing are the property of the Franklin Mineral Museum. Photographs
can be used strictly for personal use onl
y
. Otherwise, the photographs posted here are protected by U.S. Copyright Laws. They are not to be downloaded or reproduced for public use or distribution in any way without the written permission of the Franklin Mineral Museum. ---