Formula: Na3Mg(CO3)2Cl Isometric
Description: A rare carbonate mineral found in dry lake sediments and other unusual sedimentary environments.
DODGE COUNTY: A grain 0.6 cm. long found in the matrix of the Mayville oolitic iron formation was tentatively identified by Hawley and Beaven (1934) as northupite. The mineral was a cube modified by a dodecahedron along one edge, had a saline taste, a refractive index of 1.5145 and effervesced in HCl. The iron formation is exposed in old mines and outcrops in sec. 1, 12 and 13 T.11N. R.16E., east of Neda.