The remote sensing (RS) techniques have become a guiding and promising tool for mineral exploration and mapping of lithological units. The RS for mineral exploration begins with Landsat multispectral data in which the iron oxide and clay minerals associated with hydrothermal alteration zones were delineated using techniques like BR and PCA. Later, the advanced image processing techniques like spectral angle mapping, spectral feature fitting, Crosta technique and MNF transformation were successfully implemented to delineate clay, sulphate and iron oxide minerals using the shortwave infrared bands of Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) data. The thermal bands of ASTER allowed mapping of carbonate and quartz mineralogy based on their silica content. The quantitative mapping of minerals started with the advent of hyperspectral RS data like Hyperion. The recent advances in satellite sensor technology get paralleled by the development of new and innovative approaches in RS data processing and integration. The studies have opened up new methods for mineral evaluation using sustainable and eco-friendly exploitation of natural resources. This paper provides a review of RS data products and techniques widely used for geological applications.

The beach sands along the coasts of India contain large reserves of strategic minerals like ilmenite, monazite, zircon, etc. Monazite mineral is primarily used as an ore for extracting rare earths particularly cerium and lanthanum. In the present study, the chemistry and distribution of monazite found in the beach sands of Neendakara–Kayamkulam belt in Kerala, south India, is studied using advanced techniques and standardized methods. Beach sediments were collected and analyzed for the texture, and mineralogy reveals that the study area contains characteristically fine sand with maximum 98.9% total heavy minerals (THM) content with ilmenite as predominant mineral species. The content of monazite ranges from 0.1 to 1.4%. A combination of unit operations like gravity separation, magnetic separation and electrostatic separation techniques were applied to the beach sand to recover monazite mineral. The data indicate that samples show a maximum yield of about 81% for THM and 0.5% for monazite. The ED-XRF, XRD and SEM–EDS analysis gives reliable results on the chemistry of monazite. The major chemical constituents of monazite mineral like Ce₂O₃, La₂O₃, P₂O₅ corresponds to 26.658, 13.421 and 23.649%, respectively. The SEM reveals the weathering mechanism, both mechanical and chemical, occurred in monazite mineral. Advanced characterization of monazite mineral will influence positively the efficiency of determining their potential applications.

A combination of unit operations like gravity, magnetic, and electrostatic separation techniques were applied to separate strategic heavy minerals from bulk samples taken from two coastal stretches of Kappil-Varkala (KV) and Shanghumugham-Kovalam (SK) in Thiruvananthapuram, south Kerala, India. On processing the feed, the concentrate obtained contains 67.3% THM for KV and 65.15% THM for SK, out of which ilmenite predominantly exists with a yield of 45.55 and 43.6% in weight followed by other minerals like sillimanite, monazite, zircon, rutile, leucoxene, and garnet. Analysis indicates that judicious combination of unit operations like gravity, magnetic, and electrostatic separation techniques can efficiently recover heavy mineral species even from placers of smaller deposit.

Titanium dioxide (TiO₂) is one of the best semiconductor photocatalysts due to its high stability, oxidative power, non-toxicity, low cost etc. But its photocatalytic activity is limited due to rapid recombination of photo-generated electron-hole pair, wide band gap and anatase to rutile phase transformation. These disadvantages can be eliminated by introducing dopants into the TiO₂ nanocrystals. Sol-gel and hydrothermal methods can be used for the synthesis of doped and co-doped TiO₂ nanocrystals. Advanced characterization techniques can be used for the study of phase structure, optical properties, thermal properties, surface area, morphological changes and photocatalytic activity of doped and co-doped TiO₂ nanoparticles. Doping inhibits the anatase to rutile phase transformation and suppresses the recombination of photo-generated electron-hole pair which enhances the photocatalytic activity. Here we made a review on the synthesis, characterization and photocatalytic activity of La, Ce doped and co-doped TiO₂ nanoparticles.