YEATMANITE



Yeatmanite is a manganese zinc antimony silicate mineral related to katoptrite. Representative microprobe analyses of Franklin material from Dunn and Leavens (1980). Kato (1986) proposed that in his studied specimen Mn and Zn are fully ordered, but left open the possibility that there may be disorder in other specimens in which the composition has been shown to vary slightly. Sterling Hill yeatmanite has not been fully analyzed, but energy-dispersive microprobe analysis showed it to have a composition nearly identical to Franklin yeatmanite. Yeatmanite is only slightly invariant in composition, compared with the other Sb-bearing mineral here, roméite, which is host to variable amounts of non-essential, large cations.
Yeatmanite was first described by Palache et al. (1938) from Franklin. Dunn and Leavens (1980) provided additional chemical, optical, and paragenetical data and the first X-ray powder data. Yeatmanite is known from both Franklin and Sterling Hill.
Moore (1966) noted a structural relation to katoptrite, indicated it is a stuffed pyrochroite structure, and proposed a new formula. Moore et al. (1976) expanded this description, describing yeatmanite as a derivative structure of katoptrite. The crystal structure was described in detail by Kato (1986), using material studied by Dunn and Leavens (1980) and confirming Moore's model. Yeatmanite has an octahedral sheet consisting of [5 Mn and 2 Sb], sandwiched by upper and lower tetrahedral sheets consisting of Zn3Mn2Si2.
Yeatmanite occurs as lath-like crystals, almost invariably platy and wholly enclosed in other species. Maximum crystal size is approximately 1 cm, but most are quite small. Crystals rarely can be pseudohexagonal, and a common habit was illustrated by Palache et al. (1938). Yeatmanite is medium brown to dark brown, with vitreous luster, perfect cleavage, and a density of 5.04 g/cm3. There is no discernible fluorescence in ultraviolet. Yeatmanite can be confused locally with ganophyllite (which is easily distinguished by its softness), bannisterite, and franklinfurnaceite. All three minerals have unique X-ray powder patterns, and, additionally, none is known to occur in the host assemblages for yeatmanite.
Yeatmanite was first found at Franklin in willemite associated with massive pink sarkinite in a vein assemblage. This yeatmanite occurs within both willemite and sarkinite, but only where they are in contact. A second occurrence was found by John L. Baum, Resident Geologist at the Franklin Mine, at slightly below the 750 level; detailed locality data are given by Dunn and Leavens (1980). In this assemblage, it occurs as euhedral crystals, associated with diopside, andradite, and romeite, in a white matrix of massive johnbaumite. Yeatmanite has also been found with willemite and calcite in a vein in massive franklinite. In 1985, a specimen was found on the Buckwheat Dump which consisted of a layered sequence consisting of bands of (1) calcite and franklinite, (2) franklinite, and (3) a Ca-As apatite (likely johnbaumite) containing franklinite and yeatmanite.
Yeatmanite was found at Sterling Hill in 1980, as tiny brown platy crystals in two assemblages, both occurring in calcite-rich franklinite-willemite ore. It was found with willemite, adelite, and barite on the 1500 level and with tilasite, fluoborite, calcite, and willemite on the 1200 level. Although considered a rare mineral, it is likely, given its composition, that yeatmanite occurred widely distributed through both orebodies, occurring in response to localized Sb and Mn concentrations. (Dunn, 1995)

 Location Found: Franklin (Type Locality) and Ogdensburg
     
 
 Year Discovered: 1938
     
 Formula: Zn6Mn92+Sb25+(SiO4)4O12
 Essential Elements: Antimony, Manganese, Oxygen, Silicon, Zinc
 All Elements in Formula: Antimony, Manganese, Oxygen, Silicon, Zinc
     
 IMA Status: Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
     
     
 To find out more about this mineral at minDat's website, follow this link   Yeatmanite

     
 References:
Dunn, Pete J. (1995). Franklin and Sterling Hill New Jersey: the world's most magnificent mineral deposits. Franklin, NJ.: The Franklin-Ogdensburg Mineralogical Society. p.399

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.84
The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 22, No. 1 - March 1981, pg. 3Guerinite and Hawleyite from Sterling Hill, Pete J. Dunn, Yeatmanite
View IssueV. 21, No. 2 - September 1980, pg. 8Mineral Notes Research Reports, Yeatmanite
View IssueV. 17, No. 1 - March 1976, pg. 12Post Palache Mineral Review - Yeatmanite
View IssueV. 9, No. 1 - February 1968, pg. 16The Exclusive Minerals of Franklin/Ogdensburg, N.J. (as of January 1968) by Frank Z. Edwards - Yeatmanite (Short Note)
View IssueV. 8, No. 2 - August 1967, pg. 6Mineralogical Data - Yeatmanite
     
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