Geology, geochemistry and mineralogy of the Loma de Hierro Ni-laterite deposit, Venezuela

Abstract

Ni-laterite deposits host over 60% of the word land-based Ni resources (McRae, 2018). They formed from the weathering of Mg-rich ultramafic rocks exposed to the surface under favorable topography and climatic conditions. The typical Ni-laterite profile is characterized by a partially serpentinized parent rock (protolith) at the bottom followed by a saprolite horizon (dominated by secondary Si- and Mg-bearing minerals), and a limonitic horizon, dominated by goethite that evolves to hematite with time (e.g. Golightly, 2010). Ni originally liberated from olivine is concentrated in different secondary minerals such as goethite in the limonite and garnierites, secondary serpentines and/or smectite in the saprolite zone (Pelletier 1996; Villanova-de-Benavent et al. 2014). Ni-laterites are classified according to their dominant Ni-bearing ore in (a) hydrous-Mg-silicate, (b) clay and (c) oxide type deposits (Brand et al. 1998)