Until the arrival of the theories of plate tectonics and seafloor spreading in the 1960s, the Earth’s mantle was generally believed to consist of peridotites of uniform composition. This view was shared by geophysicists, petrologists, and geochemists alike, and it served to characterize the compositions and physical properties of mantle and crust as “Sial” (silica-alumina) of low density and “S...

Geologists, petrologists, geomorphologists, botanists and ecologists often collect samples through field surveys. They are required to obtain permission from the Ministry of Environment before collecting in a special zone marine park national park. For example, is necessary for sampling prior mining minerals or quarrying soil stones such zones. A legal procedure introduced that be followed taki...

A common perception among petrologists is that Al is immobile in most geologic processes, and, therefore, the conversion of gabbro with high Al-content (16-18 wt. % Al2O3) to granitic rocks with lesser Al-content (12-13 wt. % Al2O3) by Kand Si-metasomatism is not possible. The mobility of Ca, Mg, and Fe is not doubted in hydrothermal fluids, but Al is thought not to be mobile. Two different ter...

A Microsoft Excel macro is described that enables rapid recognition of common opaque minerals. The program uses ore mineralogical features such as reflectance, anisotropy, bireflectance, Vickers Hardness and morphological features (bladed crystals, zoning and twinning) to identify possible candidates from a database of 200 common ore minerals. Reflectance can be estimated from the uncorrected l...

In the last few decades, for estimation of original equilibrium conditions mantle and deep crustal rocks, several empirical as well synthetic thermometers have been proposed. Various types rocks from earth, moon or meteorites contain two coexisting pyroxenes. Petrologists long recognised potential high Ca low pyroxenes to yield thermometric calculations. Several models proposed pyroxene in deca...

[1] Knowledge about the properties of silicate melts is needed by volcanologists and petrologists to evaluate the dynamics of volcanic eruptions and magmatic processes. These properties include the solubility and diffusivity of volatile components in silicate melts, silicate melt viscosity, and the fragmentation condition. Data and models of each property are reviewed and assessed. For rhyoliti...

For centuries, theologists, historians, archaeologists, petrologists, and others had been interested in a story about Christian martyrs known as Passio Sanctorum Quattuor Coronatorum. It is a hagiographic manuscript from the 4th century which describes the martyrdom and death of two separate groups of Christians who suffered Diocletian's persecution. One group lived in Pannonia and the other in...

The history of the chemical analysis of minerals is shortly reviewed. Following rapid developments between I77O and 181o, few important changes took place for close on 13o years; new procedures led to simpler and more convenient separations but not, on the whole, to greater accuracy. The older analyses are, in general, neither worse nor better than modern ones, and analyses can only be assessed...