monaziitissa

Monazite is a phosphate mineral that contains a substantial amount of rare earth elements (REEs). Its chemical formula is generally written as (REE)PO4, with common substitutions among cerium, lanthanum, and neodymium, and often notable amounts of thorium and uranium. Monazite crystals are typically brown to reddish-brown and have a relatively high density. It crystallizes in the monoclinic system and is commonly found in igneous and metamorphic rocks as well as in sedimentary placer deposits.

In terms of physical properties, monazite is usually opaque to translucent with a resinous to adamantine luster. It behaves as a brittle mineral with a Mohs hardness around 5 to 5.5. The presence of thorium and sometimes uranium makes monazite radioactive, which has implications for handling and processing of the ore.

Monazite forms in a variety of geological settings. It occurs in granitic and pegmatitic rocks, as accessory grains, and is a major constituent of heavy mineral sands derived from the weathering and erosion of REE-rich rocks. Coastal placers in places such as Kerala in India and parts of Sri Lanka, Africa, and Brazil have long been recognized for abundant monazite-bearing sands.

Economically, monazite is an important source of rare earth elements, particularly the light to middle REEs. Extraction and processing are complicated by thorium and uranium contents, requiring careful regulatory and environmental controls. In geology, monazite is also valued for radiometric dating (U-Pb dating) because it can incorporate uranium and thorium, enabling ages to be determined for rocks and metamorphic events.