Birnessite, a sodium manganese oxide hydrate mineral, was first reported from Sterling Hill by Frondel et al. (1960a) and has not been found at Franklin or been studied since. It occurs as black crusts with other manganese oxides as a weathering product of franklinite at the Noble pit (Frondel et al., 1960). The crusts vary from dense to earthy; the earthy material is composed of minute acicular crystals and lath-like crystals. Identification is not simple; it requires X-ray and other methods. The massive, fine-grained manganese oxides are very difficult to identify visually. Much material labeled wad, psilomelane, or pyrolusite may be birnessite, todorokite, cryptomelane, feitknechtite, woodruffite, or other species. (Dunn, 1995)

 Location Found: Ogdensburg
 Formula: (Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O
 Essential Elements: Hydrogen, Manganese, Oxygen, Sodium
 All Elements in Formula: Calcium, Hydrogen, Manganese, Oxygen, Sodium
 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   Birnessite

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.584

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.45

The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 2, No. 1 - February 1961, pg. 4Birnessite (small article)

Birnessite, calcite, franklinite, and minor willemite, Sterling Hill Mine, Ogdensburg, NJ
Birnessite (red to maroon), calcite (white), franklinite (black), and minor willemite (gray) from the Sterling Hill Mine, Ogdensburg, NJ. 2 1/4" x 1 1/4". From the collection of JVF, photo by WP.

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