Tennantite



Tennantite is a copper iron arsenic sulfide mineral. Preliminary analysis of the original material yielded a composition of (Cu9.99Zn1.24Fe0.77) (As3.69Sb0.31)S13. Analysis of a specimen with loellingite, from a separate assemblage described below, yielded Cu 43.05, Zn 5.65, Fe 3.1, As 19.1, Sb 1.25, S 28.0, total = 100.15 wt. % (E. A. J. Burke, pers. comm.). This yields, on the basis of 12 (Cu,Fe,Zn), the composition (Cu9.92Zn1.27Fe0.81)(As3.73Sb0.15)S12.78, very close to the composition of the original material and demonstrating that both specimens have Zn > Fe.
Tennantite was first found at Sterling Hill by Lawson Bauer and confirmed by Palache (1928a, 1935). Reflected-light studies indicate it is commonly present as an accessory mineral in the late sulfide veins at Franklin and Sterling Hill.
Sterling Hill tennantite has been observed megascopically only on the material described by Palache (1928a). Here it occurs as 2-3 mm, equant crystals.
This tennantite is deep red, appearing black upon casual observation, and has a metallic luster and no cleavage. It could be confused with some single-crystal hematite.
The original find of tennantite was on the 900 level at Sterling Hill. Here it occurs in a vein, and coats an assemblage of actinolite, feldspar, titanite, and epidote, and is in turn coated with stilbite crystals.
Tennantite also was found intimately associated with bornite and loellingite on the 1300 level and with bornite, chalcopyrite, galena, and sphalerite on the 800 level. It was seen, but not studied, in a number of the sulfide veins, always sparse and associated with bornite and sphalerite.
Jenkins and Misiur (1994) reported it from below the 700 level, with an Sb:As ratio of 15:85, associated with chalcopyrite, galena, and other minerals. (Dunn, 1995)


 Location Found: Franklin and Ogdensburg
     
 
 Year Discovered: 1819
     
 Formula: Cu6[Cu4(Fe,Zn)2]As4S13
 Essential Elements: Arsenic, Copper, Iron, Sulfur
 All Elements in Formula: Arsenic, Copper, Iron, Sulfur, 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   Tennantite

     
 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.554

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.79


The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 35, No. 2 - Fall 1994, pg. 21A Complex Base-Metal Assemblage From the Sterling Mine New Jersey - Tetrahedrite-Tennantite
View IssueV. 34, No. 2 - Fall 1993, pg. 10Duftite From The Sterling Mine Ogdensburg, New Jersey - Tennantite
     
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