In addition to its hardness, corundum is unusual for its density of 4. The record has lab 2-3 igneous rock identification pdf been surpassed by certain synthetic boules. Corundum for abrasives is mined in Zimbabwe, Russia, Sri Lanka, and India.
Four corundum axes dating back to 2500 BCE from the Liangzhou culture have been discovered in China. In 1877 Frenic and Freil made crystal corundum from which small stones could be cut. Because of the simplicity of the methods involved in corundum synthesis, large quantities of these crystals have become available on the market causing a significant reduction of price in recent years. 982 Å at standard conditions.
The unit cell contains six formula units. In the lattice of corundum, the oxygen atoms form a slightly distorted hexagonal close packing, in which two-thirds of the gaps between the octahedra are occupied by aluminum ions. Chantilly, VA, US: Mineralogical Society of America. The Geology and Genesis of Gem Corundum Deposits”. Research Gate: Mineralogical Association of Canada. Corundum, Aluminum Oxide, Alumina, 99.
This page was last edited on 8 February 2018, at 16:52. Identification of the various grades of such materials for engineering purposes is a problem which repeatedly faces the engineer engaged in the design and construction of structures on or with laterite materials. The author has attempted to assemble available information useful for the identification and evaluation of all grades of laterite materials for engineering purposes. In the first part he summarises information on the significant genetic characteristics which appear to underlie the deviation of engineering behaviour of laterite materials from the expected properties based upon conventional soil mechanics as developed for temperate-zone soils.
The second part summarises available information on the identification of significant geotechnical properties of various grades and genetic groups of laterite materials for engineering purposes. The engineering behaviour of laterite materials forms the substance of the third part of the paper. Other significant genetic characteristics include morphological characteristics as well as the type and content of secondary minerals. Such an approach is desirable to increase the accuracy of predictions and assessments of the engineering behaviour of most laterite materials.