"Rock of the Month # 280, posted for October 2024" ---

Native Sulphur on white Celestine

from Monroe county, Michigan, U.S.A.

Sulphur (S, element 16 in the periodic table) is one of the most spectacular and abundant of the native elements, with its striking crystals and vivid yellow hue (yellow includes the wavelength of light to which the human eye is most sensitive). The most famous sulphur deposits in the world are surely those of Sicily (Pagano and Wilson, 2012). Those deposits cover a wide area, hosted in evaporite sediments of upper Miocene age. Sulphur is typically associated with calcite and with sulphates such as gypsum and celestine. Some of the deposits occur in areas affected by volcanism, but the key rock units are the evaporitic sediments. Bituminous material may be present, and sulphur may form by bacterial reduction of evaporitic sulphates, no volcanism required! Sulphur was known in ancient times, and described by such contemporary writers as Pliny the Elder (Boyle, 2024, pp.284-289).

Sulphur is widely distributed in volcanic regions both active and extinct, associated with hot spring systems and volcanism, as well as in sedimentary deposits, in which sulphur commonly occurs in oxidized form, in sulphates such as gypsum and anhydrite. Besides major deposits, sulphur may also be found in minor occurrences, as in a cavity in a Tertiary dyke in Scotland (Livingstone and Baird, 1991). Native sulphur showings are also relevant in exploration for epithermal and porphyry deposits, as in the area of Volcan Copiapo in Chile (Stark and Zentilli, 1992).

Fine sulphur and celestine specimens have been found in the Maybee area for over 100 years, though the current quarry operation at Maybee dates to 1958. Maybee, in central Monroe county, lies some 53 km southwest of Detroit in southeast Michigan. The quarry targeted Devonian dolostones and sandstones, but the deepest parts have now reached underlying Silurian limestones (see the fine illustrated review by Stefano and Barr, 2021). The host strata were deposited in a shallow sea, part of the Findlay Arch district, and the sediments dip gently into the wider structure of the Paleozoic Michigan basin, which extends far to the east across adjacent states and southern Ontario. The upper strata at the quarry are rich in celestine which, along with minor sulphur, probably formed soon after deposition of the host sediments. Karst-style dissolution of carbonate host rock formed cavities. Most of the sulphur is found in cavities of its own, and probably developed by reduction of the abundant sulphate over millions of years. The ongoing process of leaching and reprecipitation may account for the etched appearance of many sulphur specimens.

Specimens from Monroe county are highly prized, the best producing levels at Maybee being either mined-out or inaccessible, according to modern quarrying patterns. Fine specimens from at least three quarries in the county feature in the literature of mineral collectors, whether white / clear / blue celestine (Moore, 2002, 2017; Stefano, 2021, 2022) or native sulphur (Moore and Stefano, 2020).

REFERENCES

Boyle,RW (2024) A History of Geochemistry and Cosmochemistry, from Prehistory to the end of the Classical Period. Cambridge Scholars Press, Newcastle upon Tyne, England (Wilson,GC, Butt,CRM, Garrett,RG and Robinson,H, editors), 50+580pp.

Livingstone,A and Baird,WJ (1991) An occurrence of native sulphur near Craignish, Argyllshire. Scot.J.Geol. 27, 74.

Moore,TP (2002) Tucson Show 2002. Mineralogical Record 33, 261-266.

Moore,TP (editor) (2017) Mineral Collections in California. Mineralogical Record 48 no.4, supplement, 296pp.

Moore,TP and Stefano,CJ (editors) (2020) Mineral Collections in Texas, III. Mineralogical Record 51 no.6, supplement, 286pp.

Pagano,R and Wilson,WE (2012) The sulfur mines of Sicily. Mineralogical Record 43, 161-206.

Stark,A and Zentilli,M (1992) Are native sulphur deposits the crown of porphyry/epithermal precious-metal systems? A sulphur isotope test in the Miocene Volcan Copiapo complex, Maricunga district, Chile. GAC/MAC Abs. 17, 128pp., 104, Wolfville.

Stefano,CJ (2021) East Coast show. Mineralogical Record 52 no.6, 766-770.

Stefano,CJ (2022) Collector profile: Harris Precht, mineral collector and tree farmer. Mineralogical Record 53 no.3, 371-387.

Stefano,CJ and Barr,WB (2021) The Maybee quarry, Maybee, Monroe County, Michigan. Mineralogical Record 52 no.3, 251-289.