Copper



Copper was first reported from Franklin by Wolff (1898a) who described a variety of assemblages and Foote (1898) who noted an association with roeblingite, subsequently reported again by Hurlbut and Baum (1960). It was reported by Ries and Bowen (1922) from various assemblages, including that of vesuvianite (cyprine), and by Haff (1934) as occurring with hodgkinsonite and willemite. The extant data were summarized by Palache (1935). Copper is known also from Sterling Hill.
Copper occurs in hackly masses, wires, sheets, films, and finely dispersed platelets and in rare distorted crystals up to 1 cm, some of which coat datolite, as noted by Palache (1935). Pseudocrystals are also known, having resulted from copper coating crystals of other minerals. Irregularly-shaped masses are common, adopting their shape from cracks and openings in host rocks. Copper is opaque and commonly bright metallic orange when scratched, but is commonly oxidized to brown or blackish coatings; cuprite is known from such an association. Copper is readily identified by its sectility and the color of the freshly exposed material.
Copper from these deposits has been little studied. Burke and Dunn (1988) reported finely disseminated copper which contained 99.5 wt. % Cu, but few additional analytical data exist.
Although known from both deposits, most of the extant specimens, and the preponderance of material, has come from Franklin. Franklin copper is best considered in two contexts: the finely-disseminated microscopic material and the recrystallized megascopic material.
Finely disseminated copper is widespread at Franklin, occurring in a number of minerals. There is very little information on such occurrences and almost no analytical data, except that given by Burke and Dunn (1988) who noted the association with willemite, domeykite, and cuprostibite. The bulk of primary Franklin copper was likely distributed sparsely in this manner.
Most Franklin hand-specimens, however, contain megascopic copper, occurring in hackly masses up to 30 cm in size, weighing in excess of 0.5 kilograms, and forming attractive specimens. Most of these occurrences postdate the period of primary ore formation and are in recrystallized assemblages and chemically-reworked material, commonly forming vein and crack-fillers, and occurring in numerous parts of the mine. The associated minerals and the extant literature suggest that the bulk of the known specimens came from the northern end of the mine, near the Parker and Palmer Shafts; some are from the 450 level.
Copper is associated with a wide variety of minerals, too numerous to mention in entirety but including, in addition to those noted above, hancockite, leucophoenicite, calcite, datolite, franklinite, hancockite, manganaxinite, andradite, vesuvianite, andradite, willemite, zincite, barite, bustamite, and epidote. Worthy of particular mention are several assemblages, including: copper, barite, willemite and hodgkinsonite, forming attractive and much valued specimens; glaucochroite, hardystonite, and copper; and copper, calcite, hedyphane, and barylite, which constitute one of the rarer assemblages.
At Sterling Hill, native copper has been found only rarely, associated with secondary arsenates, such as sarkinite, in vein assemblages. Other occurrences likely exist.
Some unnatural-shaped specimens exist in collections; these are the result of plates of copper having passed through the crushers at the mills. (Dunn, 1995)


 Location Found: Franklin and Ogdensburg
     
 
     
 Formula: Cu
 Essential Elements: Copper
 All Elements in Formula: Copper
     
 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   Copper

     
 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.520

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.52


The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 42, No. 1 - Spring/Fall 2001, pg. 25A Classic Native Copper From Franklin, New Jersey by John L. Baum
View IssueV. 19, No. 2 - September 1978, pg. 6Recent Mineral Occurrences at Sterling Hill by Stephen Sanford - Native Copper Crystals (small article)
View IssueV. 16, No. 1 - February 1975, pg. 9Mineral Notes - Native Copper
     
Images

     
Copper, willemite and calcite  from Franklin, NJ.Copper, willemite and calcite  from Franklin, NJ. under shortwave UV Light
Copper, willemite (green, white) and calcite (white) from Franklin, NJ. 5" x 4". From the collection of, and photo by Robert A. Boymistruk.
Copper, willemite and calcite from Franklin, NJ under shortwave UV light. The willemite fluoresces green and the calcite red, copper is non-fluorescent. 5" x 4". From the collection of, and photo by Robert A. Boymistruk.


Copper, willemite, franklinite and minor zincite from Franklin from Franklin, NJCopper, willemite, franklinite and minor zincite from Franklin from Franklin, NJ under shortwave UV Light
Copper, willemite (light green), franklinite (black) and minor zincite (red-brown) from Franklin, NJ. 4 1/4" x 2 1/8". From the collection of, and photo by Robert A. Boymistruk.
Copper, willemite, franklinite and minor zincite from Franklin from Franklin, NJ under shortwave UV light. The willemite fluoresces green, the copper, franklinite and zincite are non-fluorescent. 4 1/4" x 2 1/8". From the collection of, and photo by Robert A. Boymistruk.


Copper, willemite, franklinite and gemmy hodgkinsonite from Franklin, NJCopper, willemite, franklinite and gemmy hodgkinsonite from Franklin, NJ under shortwave UV Light
Copper, willemite (white to light green, gemmy), franklinite (black) and gemmy hodgkinsonite (purple) from Franklin, NJ. 2" x 1 1/2". From the collection of, and photo by WP.
Copper, willemite, franklinite and gemmy hodgkinsonite from Franklin, NJ under shortwave UV light. The willemite fluoresces green, the copper, franklinite and hodgkinsonite are non-fluorescent. 2" x 1 1/2". From the collection of, and photo by WP.


Copper, willemite, franklinite and minor calcite from Franklin, NJ.Copper, willemite, franklinite and minor calcite from Franklin, NJ. under shortwave UV Light
Copper (reddish-brown), willemite (white), franklinite (black) and minor calcite (white) from Franklin, NJ. 7" x 4". From the collection of, and photo by Robert A. Boymistruk.
Copper, willemite, franklinite and minor calcite from Franklin from Franklin, NJ under shortwave UV light. The willemite fluoresces green, calcite weak orange, the copper and franklinite are non-fluorescent. 7" x 4". From the collection of, and photo by Robert A. Boymistruk.







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