Greenockite is a cadmium sulfide mineral isostructural with wurtzite. Local material has not been analyzed, except for the crystals from Sterling Hill which Dunn (1979c) noted to have a Cd:Zn ratio of 3:2.
Greenockite was noted as an unconfirmed species by Canfield (1899) and Palache (1908, 1935), but this material has been found to be a mixture including hawleyite. Kunz and Baskerville (1903) refer to a fluorescent greenockite from Franklin, but no data are given, and the description is of limited utility.
Greenockite is yellow to orange-yellow and occurs as powdery encrustations and thin films for the most part. The uncommon zincian greenockite described by Dunn (1979c) occurs in prismatic, subhedral crystals. Most local greenockite occurs intimately associated with other minerals, chiefly sphalerite, and thus historical observations of apparent fluorescence may be due to mixtures with other minerals.
The "greenockite" reported by Palache (1935) from the Hamburg Mine, later part of the Franklin Mine, is shown here to be a mixture of sphalerite and hawleyite. True greenockite likely occurs here or elsewhere in the Franklin Mine in traces.
A number of greenockite specimens have been found at Sterling Hill, but this does not indicate a predominance of greenockite here relative to Franklin. Dunn (1979c) described a zincian greenockite occurring in small crystals associated with euhedral crystals of galena which, with greenockite, coat botryoidal sphalerite which in turn coats calcite. Numerous other occurrences have been found at Sterling Hill, particularly on the 1400 level, and most are associated with sphalerite and/or galena. (Dunn, 1995)

 Location Found: Franklin and Ogdensburg
 Year Discovered: 1840
 Formula: CdS
 Essential Elements: Cadmium, Sulfur
 All Elements in Formula: Cadmium, Sulfur
 IMA Status: Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Fluorescent Mineral Properties

 Longwave UV light: Cherry red
 To find out more about this mineral at minDat's website, follow this link   Greenockite

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.533

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.59

The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 57, No. 2 - Fall 2016, pg. 18Fluorescent Minerals of Franklin and Sterling Hill, N.J., Part 1, Richard C. Bostwick - Greenockite
View IssueV. 51, No. 1 - Spring 2010, pg. 8A Forensic Analysis of Purported Greenockite (Cadmium Sulfide) From Sterling Hill
View IssueV. 20, No. 2 - September 1979, pg. 8Contributions to the Mineralogy of Franklin and Sterling Hill New Jersey, Greenockite (small article)

Greenockite, willemite, calcite, franklinite, Franklin, NJ
Greenockite (golden yellow), willemite (pink to reddish brown), calcite (white), and franklinite (black), from Franklin, NJ. Actual image width 2" (25 mm). From the collection of, and photo by WP.

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