DYPINGITE
Mg5(CO3)4(OH)2 · 5H2O,
magnesium carbonate hydroxide hydrate
Dypingite was first described as a mineral species in 1970 and nine years later was confirmed from the North Orebody at Sterling Hill by Dunn (1979), who investigated a specimen brought to his attention by miner Richard Bostwick. As in other occurrences worldwide, it forms small white hemispherules on fracture surfaces and is a late-stage mineral. Dunn (1979) called attention to the tendency of dypingite to form curving tracks of minute hemispherules, well shown in several specimens below, and noted that the tracks did not seem to follow grain boundaries in the underlying matrix rock. He further noted that the minute spherules when broken show a fibrous texture and are “composed of acicular crystals radiating from a common origin.” The mention of a fibrous texture and acicular crystals is puzzling inasmuch as an SEM image of one dypingite hemispherule in the same paper shows it to be composed of thin, leaflike crystals. Dunn (1995) later amended his description to “flattened crystals.”
The great preponderance of dypingite specimens from the Franklin-Sterling Hill area came from the Sterling mine. Dypingite is apparently rare from Franklin, but Bostwick (2016) mentioned a single find of the mineral on the site of mill no. 2 (“Palmer mill”) in Franklin, where it occurred on a matrix “rich in green serpentine.” This is reminiscent of its occurrence as a surface alteration product of serpentine at the type locality of the species in Snarum, Norway (see https://www.mindat.org/min-1338.html). Nearly all other local dypingite, however, occurs as thin coatings on fracture surfaces in zinc ore, either hydrothermally altered ore from the North orebody in the Sterling mine, or from “red ore” (so-named because of its content of reddish-brown to brownish-red willemite) from the main workings at higher levels (Bostwick, 2016). Specimens are uncommon, and good ones rare, though occasionally one will surface from an old collection.
Dypingite in all local specimens examined thus far fluoresces, as noted first by Dunn (1979) and later elaborated on by Bostwick (1992, 2016) and Bostwick and King (2022). The fluorescence is usually described as “moderately bright very pale blue” or “moderately bright pale blue to white SW, MW, and LW.” Dunn noticed no phosphorescence in his original 1979 description, but later authors consistently mention phosphorescence following SW, MW, and LW excitation, probably due to viewing specimens under the much more powerful UV lamps then in use. It should be noted that these characteristics do not serve as an identifying feature of dypingite, as other white, fracture-coating minerals from the local area, including calcite, aragonite, smithsonite, and hemimorphite, show a similar response in some specimens. Nevertheless, the botryoidal habit and tendency of dypingite to occur in chainlike tracks is a partially useful characteristic for recognizing it.
References
Bostwick, R.C. (1992), The check list of Franklin-Sterling Hill fluorescent minerals: discussion and update. The Picking Table, vol. 33, no. 2, p. 4-11. [Mentions pale blue fluorescence of dypingite on p. 10]
Bostwick, R.C. (2016), Fluorescent Minerals of Franklin and Sterling Hill, N.J., Part 1. The Picking Table, vol. 57, no. 2, p. 10-22. [Brief description of dypingite on p. 16; notes that Sterling Hill was the source of almost all dypingite specimens]
Dunn, P.J. (1979), Contributions to the mineralogy of Franklin and Sterling Hill, New Jersey. Mineralogical Record, vol. 10, no. 3, p. 160-165. [First report of dypingite in the Franklin-Sterling Hill area]
Dunn, P.J. (1995), Franklin and Sterling Hill, New Jersey: the world’s most magnificent mineral deposits. Privately published in five volumes, 755 pp. [Two-paragraph description of dypingite on p. 620]
King, V.T., King, N.E., Betancourt, P.P., Bostwick, R.C., Chin, Peter, Hecht, T.J., Kuitems, S.M., Moritz, H., Nemetz, J.D., Nikischer, A.J., Sanford, S., Van Fleet, J.A., and Verbeek, E.R. (2021), The Mineralogy of Franklin and Ogdensburg, New Jersey—A Photographic Celebration. Privately published, 1400 pp. [Repeats information from the 2016 Bostwick paper on p. 17 in chapter 2. Photos of fluorescent dypingite specimens on p. 97-98; see also p. 858]
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