Mottramite is an orthorhombic mineral at the copper end of the Descloizite group. It was previously called Cuprodescloizite or Psittacinite. It was characterized by Frederick Augustus Genth in 1868. This secondary mineral is regularly found mainly in the oxidized zones of ore deposits. Plumose - "Mica-like" minerals form aggregates of plume-like forms. Radial crystals emit from a center without creating stellar forms (e.g. stibnite)
PbCu (VO4) (OH)
Derivation of Name
It was most probably named after the area of Mottram St. Andrew, Cheshire, England, where the ore was stored. Most probably it got mined from Pim Hill Mine, Shrewsbury, and Shropshire.
Generally found in minute Druze crusts, as shining and Stalactitic masses, the Mottramite series are normally linked with Wulfenite and Vanadinite in the normal secondary mineral suites from oxidized areas of ore deposits. It is mainly prevalent in both Arizona and New Mexico, and is frequently found crusting the rock matrix of Vanadite and Wulfenite.
Probably stocks of this ore were found in England, at Mottram St. Andrew, Cheshire and mined from the close by Pim Hill mine, Shrewsbury, Shropshire. Famous occurrences are: Pinal County, Arizona, USA; Bolivia, Chile; England and different places.
Mottramite is an end member of a series comprising of the mineral Descloizite. It’s a copper rich end member, whereas Descloizite is a zinc rich member. Both minerals typically include considerable percentages of both the elements and are seldom unadulterated. Of the two, Mottramite is rarer and can form radiant crusts with a good luster and arresting green color. Since it is rare and attractive its price is generally higher.
Grass-green, yellow-green, olive-green, siskin-green, nearly black or blackish brown.
Mohs scale hardness
3 - 3½