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In both conventional and in-situ dating, a thin section of the rock of interest is prepared. [2] First, a thin layer of rock is cut by a diamond saw and ground to become optically flat. Then, it is mounted on a slide made of glass or resin, and ground smooth using abrasive grit. The final sample is usually only 30 μm thick. [2]
Monazite is an important ore for thorium, [8] lanthanum, and cerium. [9] It is often found in placer deposits. India, Madagascar, and South Africa have large deposits of monazite sands. The deposits in India are particularly rich in monazite. Monazite is radioactive due to the presence of thorium and
QAPF diagram for classification of intrusive igneous rocks, with the monzonite field highlighted Photomicrograph of thin section of monzonite (in cross polarised light) Photomicrograph of thin section of monzonite (in plane polarised light) The Notch Peak monzonite intrusion in Utah inter-fingers (partly as a dike) with highly metamorphosed Cambrian carbonate host rocks
Bastnäsite and the phosphate mineral monazite are the two largest sources of cerium and other rare-earth elements. Bastnäsite was first described by the Swedish chemist Wilhelm Hisinger in 1838. It is named for the Bastnäs mine near Riddarhyttan, Västmanland, Sweden. [3]
In the study of metamorphic petrology, uranium–thorium–lead dating of monazite (monazite geochronology) is an effective method to determine the P-T history. [ 29 ] [ 30 ] Monazite is a phosphate mineral containing light rare-earth-elements (LREE) that occurs in a wide range of rock types. [ 31 ]
Thin sections are prepared in order to investigate the optical properties of the minerals in the rock. This work is a part of petrology and helps to reveal the origin and evolution of the parent rock. A photograph of a rock in thin section is often referred to as a photomicrograph.
It is the cerium-dominant analogue of monazite-(La), monazite-(Nd), and monazite-(Sm). It is also the phosphorus analogue of gasparite-(Ce). [ 3 ] The group contains simple rare earth phosphate minerals with the general formula of AXO 4 , where A = Ce, La, Nd, or Sm (or, rarely, Bi), and X = P or, rarely, As.
The thin section has been slightly rotated to show the characteristic change in color of the tourmaline known as pleochroism. Figure 5c. Cross-polarized light photomicrograph of tourmaline in sample CV-114 from the Strathbogie Granite