Richterite is a sodium calcium magnesium silicate hydroxide mineral of the amphibole group. Foshag reported an analysis with considerably more Al2O3 than [Dunn] has obtained for identical specimens. Some Franklin richterites have compositions near a midmember with richterite:winchite near 1:1.
Richterite is a rare amphibole locally; it is known from only one assemblage. The original report was by Foshag (1936), who described it as a zincian amphibole.
Franklin richterite occurs as euhedral crystals, up to 4 x 1 cm. It is very dark green to nearly black, with vitreous luster, and normal amphibole prismatic cleavages.
Richterite has been found only with bannisterite, which was known to Foshag (1936) as a variety of ganophyllite. In this assemblage it occurs as prominent crystals, in both a feldspar matrix and within the brown platy bannisterite. (Dunn, 1995)

 Location Found: Franklin
 Year Discovered: 1865
 Formula: {Na}{CaNa}{Mg5}(Si8O22)(OH)2
 Essential Elements: Calcium, Hydrogen, Magnesium, Oxygen, Silicon, Sodium
 All Elements in Formula: Calcium, Hydrogen, Magnesium, Oxygen, Silicon, 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   Richterite

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.458

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