Sillimanite is a very important raw material for the manufacture of refractory bricks used in iron and steel, cement and glass industries. In some coastal stretches of south India, the beach sand is contaminated with shell. After recovering heavy minerals like ilmenite, rutile, zircon and garnet by various physical separation techniques, the final sand containing sillimanite, quartz and shell i...

The red sand which is known as Teri sand in Tamil Nadu consists of 5.5% Total Heavy Minerals (THM) out of which 3.7% is ilmenite. The other minerals, zircon, sillimanite and garnet are in the order of abundance identified. On processing this feed to recover ilmenite by using spirals followed by dry high intensity magnetic separator and high tension separator, the ilmenite concentrate obtained c...

R.T. Downs Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Abstract The unit-cell dimensions and crystal structure of sillimanite at various pressures up to 5.29 GPa have been refined from single-crystal X-ray diffraction data. As pressure increases, a and b decrease linearly, whereas c decreases nonlinearly with a slightly positive curvature. The axial compression ...

Different models are discussed to interpret the presence of kyanite as a stable phase in contact aureoles especially in the andalusite-, sillimanitebearing aureoles. In such aureoles the polymorphic sequence kyanite → andalusite → sillimanite can be explained in terms of an essentially isobaric path during which kyanite initially crystallises from the breakdown of pyrophyllite or more likely mu...

Phase equilibria modelling incorporating melt reintegration offers a methodology to create hypothetical rock compositions that may have existed prior to melt loss, allowing the potential prograde evolution of rocks to be explored. However, melt reintegration modelling relies on assumptions concerning the volume of melt that was lost and is generally restricted by the absence of direct constrain...

Wherry discussed the origin of this material and on the basis of mineralogical and structural evidence suggested its derivation from aan original sedimentary type. He concluded that the presence of sillimanite indicated a noteworthy alumina content of the original sediment and thought that very likely the material w’as originally an argillaceous sandstone. The present writer” has discussed the ...

Using theoretical simulations based on density functional theory within the generalized gradient approximation, a series of metastable phase transitions occurring in low-pressure Al2SiO5 polymorphs (andalusite and sillimanite) are predicted; similar results were obtained using semiclassical interatomic potentials within the ionic shell model. Soft lattice modes as well as related structural cha...