Pyrophanite



Pyrophanite is a manganese titanium oxide mineral and the Mn-analogue of ilmenite. Craig et al. (1985) reported four closely agreeing analyses, with approximately 2.5 wt.% FeO and 1.6 wt. % ZnO and trace amounts of Si, Al, K, Na, and Ca. Valentino (1983) reported similar Zn-concentrations, but with markedly higher Fe contents; he also presented a discussion of contamination possibilities. Therefore, to date, there is little evidence of solid solution toward ZnTiO3, such as was found in China by Suwa et al. (1987).
Pyrophanite was first reported from Sterling Hill by Sandhaus (1981) and Craig et al. (1985) and was later reported by Valentino (1983) and Valentino et al. (1990). It has not been reported from Franklin.
Pyrophanite occurs as subhedral aggregates or microscopic grains up to 2 mm in diameter, but most are much smaller. They are black, opaque, and have metallic luster. Reflectance and microhardness data were given by Craig et al. (1985).
The occurrence reported by Sandhaus (1981) and Craig et al. (1985) was found near the 500 level of the Sterling mine. The matrix is greenish-gray Mn-bearing augite associated with gahnite, hendricksite, and calcite. Pyrophanite occurs within the augite.
Valentino (1983) and Valentino et al. (1990) reported pyrophanite exsolved in magnetite lamellae, which are themselves part of a magnetite-franklinite exsolution. His specimens were also found on the 500 level at Sterling Hill, approximately 10 feet east along the cross-cut from the west limb. The rock at this site is marble containing diopside, franklinite, gahnite, mica, and garnet. (Dunn, 1995)


 Location Found: Ogdensburg
     
 
 Year Discovered: 1890
     
 Formula: Mn2+TiO3
 Essential Elements: Manganese, Oxygen, Titanium
 All Elements in Formula: Manganese, Oxygen, Titanium
     
 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   Pyrophanite

     
 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.603


The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 28, No. 1 - Spring 1987, pg. 26Pyrophanite Mode of Occurrence and Physical Properties (small article)
     
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