Akrochordite is a manganese arsenate hydroxide hydrate mineral. Local material contains very little Mg.
Akrochordite was first reported from Sterling Hill by Dunn (1981b); it has not been reported from Franklin.
Akrochordite occurs as spherical aggregates of platy crystals with a radial texture, but only one near-complete spherule (approximately 12 mm in diameter) is known. The preponderance of local material occurs as flattened, round, 5-7 mm splayed patches in vein assemblages; these aggregates have varying thicknesses and curved edges, suggesting that they were prevented from developing into hemispherulitic aggregates by tight vein sidewalls. The color is very light brown, but akrochordite is easily oxidized, and surface colors are much darker brown. The density is 3.35 g/cm3. There is no discernible fluorescence in ultraviolet. It is best identified using X-ray methods.
Akrochordite occurs rarely in veins in calcite-rich willemite-franklinite ore, associated with sarkinite, chlorophoenicite, and a carbonate mineral. It was found in 1979 in the 1220 undercut pillar, 30 feet below the 800 level. (Dunn, 1995)

 Location Found: Ogdensburg
 Year Discovered: 1915
 Formula: (Mn2+,Mg)5(AsO4)2(OH)4 · 4H2O
 Essential Elements: Arsenic, Hydrogen, Manganese, Oxygen
 All Elements in Formula: Arsenic, Hydrogen, Magnesium, Manganese, Oxygen
 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   Akrochordite

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.655

The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 36, No. 1 - Spring 1995, pg. 9Closest-Packing and Hydrogen Bonds in Minerals of the Franklin Marble, Paul B. Moore - Akrochordite
View IssueV. 22, No. 2 - September 1981, pg. 7Mineral Notes Research Reports, Akrochordite
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