Titanite



Titanite is a calcium titanium silicate mineral. Partial microprobe analyses of Franklin titanites indicate that some samples are highly aluminian (up to 8 wt. % Al2O3), and some have 2-5 wt. % FeO. Analysis of a titanite associated with margarite yielded SiO2 31.8, Al2O3 6.74, TiO2 26.28, FeO <0.03, MnO 0.09, MgO 0.14, CaO 33.39, F 1.74, Cl 0.03, H2O+(calc.) 0.70, less O = F 0.73, corrected total = 100.15 wt. % (Yau et al., 1984).
Titanite was first reported from Franklin by Nuttall (1822) and Vanuxem and Keating (1822b). Specimens are not common from Franklin or Sterling Hill, although titanite is found at both deposits in the magnetite deposits, in the Franklin Marble, and in the gneisses. In general, such rock-forming minerals were undercollected relative to the more exotic local species. The preponderance of specimen material is from the Franklin Marble. Some specimens have been labeled sphene.
Franklin titanite has been little studied. Palache (1935) gave morphological data and illustrated some fine crystals. The color is commonly brown; the luster is vitreous to adamantine; and the cleavage is fair to good. It commonly occurs in well-formed, isolated euhedral crystals. The preponderance of such crystals (from x mm up to 5 cm) have typical titanite habit and morphology. Frondel (1972) reported crystals up to 15 cm. Bostwick (1992) reported a weak yellow-orange fluorescence in shortwave ultraviolet; many specimens are non-fluorescent.
Many specimens are one-of-a-kind; there is not a special or unique assemblage. Palache reported titanite occurring in pegmatites at both zinc orebodies and in the iron mines, presumably those on Balls Hill.
Franklin specimens are found with both red-fluorescent calcite (from or near the orebody) and non-fluorescent calcite (from the distal Franklin Marble). The best specimens came from the Trotter Mine (Palache, 1935). Commonly associated minerals in orebody specimens include calcite, Ti-free aegirine-augite, andradite, and minor willemite. Commonly associated minerals in marble assemblages include dolomite, fluorite, tremolite, margarite, phlogopite, uvite, pyrrhotite, graphite, and scapolite; fine crystals were found in the Franklin Iron Company Quarry. Frondel (1972) noted that it also occurs in the local gneisses as a common accessory mineral.
At Sterling Hill, titanite was found as dull green blebs in the corundum/margarite assemblage of the Franklin Marble by Dunn (1979c) and Dunn and Frondel (1990), and it also occurs as an accessory mineral with tennantite. Johnson (1990) reported titanite with 4.3 wt. % Al2O3 associated with wollastonite from beneath the east limb on the 1400 level, at the 1060 crosscut. (Dunn, 1995)


 Location Found: Franklin and Ogdensburg
     
 
 Year Discovered: 1795
     
 Formula: CaTi(SiO4)O
 Essential Elements: Calcium, Oxygen, Silicon, Titanium
 All Elements in Formula: Calcium, Oxygen, Silicon, Titanium
     
 IMA Status: Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
     
Fluorescent Mineral Properties

 Shortwave UV light: Weak yellow-orange
     
 To find out more about this mineral at minDat's website, follow this link   Titanite

     
 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.383

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.80


The Picking Table References
 PT Issue and PageDescription / Comment
V. 58, No. 1 - Spring 2017, pg. 20Fluorescent Minerals of Franklin and Sterling Hill, N.J., Part 2, Richard C. Bostwick - Titanite
View IssueV. 33, No. 2 - Fall 1992, pg. 11The Check List of Franklin-Sterling Hill Fluorescent Minerals - Titanite (Fluorescent Info)
View IssueV. 32, No. 1 - Spring 1991, pg. 9An Uncommon Margarite/Corundum Assemblage From Sterling Hill, New Jersey, Pete J. Dunn, Clifford Frondel, Titanite (small description)
View IssueV. 30, No. 1 - Spring 1989, pg. 9The Epidote-Pyroxene-Fluorapophyllite Assemblage in the Franklin Mine at Franklin, New Jersey, Philip P. Betancourt, Titanite (small description)
View IssueV. 27 No. 2 - Fall 1986, pg. 10Minerals of the Franklin Quarry, Philip P. Betancourt, Titanite
     
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