Heavy Mineral Analysis provides full analytical services including the separation of the “heavy” and “light” fraction of sand and the determination of the individual heavy minerals. Check out this website and discover the intriguing world of sand.
Sand is composed of many mineral particles. These mineral particles are released from their source rocks after prolonged periods of weathering and erosion. The liberated mineral particles are transported downstream by rivers where they settle down in an environment of deposition. As a result, the composition of sand is determined by the type of source rocks, the intensity of weathering and hydraulic sorting during transportation.
Most sands are composed for 99% of light minerals such as quartz (s.g. 2.65) and feldspar (s.g. 2.54 – 2.76). Therefore, sands are mainly distinguished on the basis of their variable heavy mineral content. Heavy minerals are considered to be those minerals with a specific density greater than 2.8.
Heavy minerals are separated from the lighter quartz and feldspar by immersion in a heavy liquid (2.8g/ml). The separation is carried out in a separation funnel. Heavy minerals sink to the bottom, while lighter minerals float to the surface. The residue of heavy minerals is drained by opening the tap at the bottom of the separation funnel. The obtained heavy minerals are mounted on microscope slides for microscopic identification. Identification occurs on the basis of optical properties under a polarizing microscope. Photos of the optical properties serve as a proof of identification.
By counting the relative abundances of the different heavy minerals, conclusion can be drawn about the source rocks, degree of weathering and hydraulic sorting. Sometimes intense weathering or hydraulic sorting results in the concentration of economically valuable minerals, so called placers. Systematic sampling and analysis of the heavy mineral content can locate potential economic deposits.