Pharmacosiderite, a potassium ferric-iron arsenate hydroxide hydrate mineral, was found in moderate abundance near the 340 level at Sterling Hill and later near the 180 level. It occurs as minute 0.3-0.8 mm cubic crystals, light green to light yellow, with a vitreous luster. Yellowish brown druses were locally abundant. It was verified by Dunn in 1973 employing only X-ray methods. Pharmacosiderite occurs associated with sphalerite, koettigite, legrandite, ogdensburgite, and other arsenates. (Dunn, 1995)

 Location Found: Ogdensburg
 Year Discovered: 1813
 Formula: KFe43+(AsO4)3(OH)4 · 6-7H2O
 Essential Elements: Arsenic, Hydrogen, Iron, Oxygen, Potassium
 All Elements in Formula: Arsenic, Hydrogen, Iron, Oxygen, Potassium
 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   Pharmacosiderite

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.677

The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 19, No. 2 - September 1978, pg. 5Recent Mineral Occurrences at Sterling Hill by Stephen Sanford - Pharmacosiderite (small article)
View IssueV. 14, No. 1 - February 1973, pg. 8Mineral Notes - Pharmacosiderite (small article)

Pharmacosiderite, calcite and willemite from Sterling Hill Mine, Ogdensburg, NJ
Pharmacosiderite (green cubes), calcite (white, brown) and willemite (dark brown) from Sterling Hill Mine, Ogdensburg, NJ. Field of view 3/4". From the collection of, and photo by Robert A. Boymistruk.

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