Deposit Model for Heavy-Mineral Sands in Coastal Environments

Abstract

This report provides a descriptive model of heavy-mineral sands, which are sedimentary deposits of dense minerals that accumulate with sand, silt, and clay in coastal environments, locally forming economic concentrations of the heavy miner­als. This deposit type is the main source of titanium feedstock for the titanium dioxide (TiO₂) pigments industry, through recovery of the minerals ilmenite (Fe²⁺TiO₃), rutile (TiO₂), and leucoxene (an alteration product of ilmenite). Heavy-mineral sands are also the principal source of zircon (ZrSiO₄) and its zirconium oxide; zircon is often recovered as a coproduct. Other heavy minerals produced as coproducts from some deposits are sillimanite/kyanite, staurolite, monazite, and garnet. Monazite [(Ce,La,Nd,Th)PO₄] is a source of rare earth elements as well as thorium, which is used in thorium-based nuclear power under development in India and elsewhere.

This report is intended to provide an overview of the principal geological, mineral resource, and environmental characteristics of the deposit type commonly referred to as heavy-mineral sands. The report is part of an effort by the U.S. Geological Survey Mineral Resources Program to update existing mineral deposit models and develop new descriptive models as needed.

First posted September 17, 2014