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Margarosanite is a rare mineral found at Franklin, but not Sterling
Hill. It fluoresces a beautiful bright blue-white under short-wave
ultraviolet light.
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Daylight view
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Margarosanite, in
lamellar masses, fluorescing bright blue-white under short-wave UV. Franklin, NJ. Width
10
cm.
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Samples are generally of one of two types:
diffuse (and invisible in daylight) disseminations within feldspar, or as coarsely
crystalline blades and plates. Specimens of the later habit are particularly prized
locally. In some cases, such margarosanite plates may fluoresce with an anomalous pinkish
color.
Masses of coarsely crystalline plates up to 4 cm
across are known. Such samples came from a restricted occurrence in the northern part of
the Franklin mine. These samples of platy margarosanite are included in what is today
referred to as "Parker shaft minerals" by local mineral collectors.
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Daylight view
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Margarosanite and
wollastonite, fluorescing bright blue-white and orange, respectively, under short-wave UV.
Franklin, NJ. Width 11 cm. |
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Some samples of platy margarosanite contain
associated secondary fluorescent wollastonite and willemite. Others may contain
minehillite or other ill-defined, fine-grained fluorescent minerals that can make very
attractive fluorescent specimens.
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Daylight view
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Margarosanite and wollastonite, detail from above sample. Some plates of margarosanite have a pinkish cast.
Franklin, NJ. Width 4 cm.
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Be sure to visit the photo
page taken under shortwave ultraviolet light.
For more information on margarosanite, see Dunn
(1995) and Palache (1935).
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