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Mineral F (of Dunn)


Mineral F (of Dunn)

Description Tabs

Sterling Mine, Ogdensburg, Sussex County, New Jersey, United States of America
Crystals on Matrix
Size Range: 
Small miniature (3-4.5 cm)
2.5 × 3 × 3.5 cm

Hemi-spheroids of Mineral F to about 1? mm. (In the photos, you are looking at the more or less flat “bottoms” of the spheroids.) FOV in the main photo is 6.9 x 4.3 mm. Mineral F is a rather odd beast in that it is a valid mineral, yet has no name (apart from its designation as UM1986-10-CO:ClHMgMnZn) – see Mindat. Will it ever have a name? At the moment, all I can say is that mineralogists don’t seem to be very eager to do whatever it is that still needs to be done in order to publish it with a name. However, to the extent that such a mineral can be “verified” via EDS, this has been done on a sample from another find. (While there are significant differences between the finds - most notably association with chlorophoenicite rather than fluoborite - the visual appearance, reaction to HCl, etc., are identical.) The mottled “leopard spots” are characteristic of Mineral F from both finds. They may indicate the first stages of alteration, which, in the case of this find, appears to lead to ugly brown spheroids of undetermined composition. (None here.) The black area in the upper left corner may be a thin sheet of hetaerolite. Such sheets commonly form along parting planes of Sterling Hill zincite. How such sheets formed here is a mystery (to me at any rate). The pinkish material may be rhodochrosite (or another carbonate that does not fizz in cold HCl). There are also a few glassy needles of fluoborite. Fluoborite is common in this find and was XRD verified. But there is not much of it here. Weight 0.8 oz.

Mineral Data
What's on the rock

Mineral F (of Dunn)

Synonym Of: 


Mg5(Zn,Mn)3(CO3)2(OH,Cl)12 · H2O
Mg5(Zn,Mn)3(CO3)2(OH,Cl)12 · H2O
LMB minerals

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In addition to the standard terms and conditions, please note the following. Almost all IDs are visual. While in most cases the ID is obvious, there may be cases where it is not. If you are doubtful about a particular ID, please ask for more information. Or do not bid! Similarly, if you are not sure that the specimen meets your criteria, do not bid. I have tdone the best I can with the photos. Nevertheless, if you are not happy with a specimen for any reason, I will refund the bid price – but not the shipping costs (unless the fault is clearly mine) – if the specimen is returned. This policy applies even if analysis of the specimen shows that my ID was incorrect. When in doubt, ask - or don’t bid. Note that most crystals at MSH and Varennes are micros - even if on large specimens. Please pay attention to the stated sizes. Any customs duties, fees etc. are the responsibility of the buyer.