La Esperanza: a new mineralization with Ni–Co in Sonora, Mexico

Abstract

A mineralized locality with Ni–Co values that could be economic is reported for the first time in Sonora. The La Esperanza ore deposit, located at 12 km NW from Bacanora, is a skarn type deposit developed at the contact between a laramidic granitoid and Paleozoic limestones. The elements Ni and Co are present as siegenite with the composition (Ni_2.05 Fe_0.19Co_0.75)_2.99S_3.97. Copper, zinc and iron sulphides are also present. The economic preliminary potential at La Esperanza is about some millions of tons with 1 gr Au/ton, 1–2 % Cu, 1–2 % Zn, 0.1–0.2 % Ni y 0.1–0.2 % Co. The Co–Ni anomalies recently found in stream sediments of the region indicate new potential targets for the regional exploration.