Legrandite, a zinc arsenate hydroxide hydrate mineral, was found on the 340 level at Sterling Hill, and verified using X-ray methods, which are suggested for identification. No physical, optical, or chemical data have been published.
Legrandite occurred as deep yellow to light yellow to colorless, flattened, splayed aggregates of lustrous, prismatic crystals, in a habit similar to that of koettigite, with crystal curvature commonly visible in the composite aggregate, and forming continuous, albeit thin, sheets of material coating many square cm of vein surfaces. Some aggregates were 3-4 mm thick, deep yellow, and slightly waxy in luster. Associated minerals are predominantly koettigite and pharmacosiderite, but small amounts of the associated species listed under koettigite are also found.
Legrandite was found again, some 5 years later, near the 180 level, where it is much more abundant, occurring in sparse euhedral crystals to several mm, and is associated with koettigite and pharmacosiderite. It has not been reported from Franklin. (Dunn, 1995)

 Location Found: Ogdensburg
 Year Discovered: 1932
 Formula: Zn2(AsO4)(OH) · H2O
 Essential Elements: Arsenic, Hydrogen, Oxygen, Zinc
 All Elements in Formula: Arsenic, Hydrogen, Oxygen, Zinc
 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   Legrandite

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.671

The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 14, No. 2 - August 1973, pg. 6Mineral Notes Recently Validated - Legrandite (small article)

Legrandite, calcite, franklinite, and willemite, Sterling Hill Mine, Ogdensburg, NJ
Legrandite (yellow coating), calcite (light gray), franklinite (black), and willemite from the Sterling Hill Mine, Ogdensburg, NJ. Field of view 1 3/4". From the collection of JVF, photo by WP.

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