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Every substance is associated to emission of electromagnetic radiation whose peaks are essentially influenced by temperature. Hot bodies (i.e., at T >700 °C) emit electromagnetic radiation in the field of visible light (incandescent light). The radiation emitted by cold bodies (i.e., at normal ambient conditions) in the visible light range is defined as luminescence. Luminescent light is emitted by exciting substances by means of electron fluxes (e.g., those generated in a cathode ray tube), using photon fluxes associated to electromagnetic radiations with wavelengths lower than ~390 nm (fluorescence), by mechanical stress (triboluminescence), by small temperature increase (thermoluminescence) or by biological processes (bioluminescence). The value of luminescence demonstrations in teaching is unique. Indeed, by illuminating specific minerals and other substances (such as chicken eggs, seashells, fossils, wood, scorpions, soda drinks) with non expensive ultraviolet (UV) lights, it is possible to introduce the audience to several scientific arguments. Among these, the most important are: a) the concept of radiation and electromagnetic spectrum, including the ?- and x-ray as well as the radio wave extremes; b) the discovery and the essence of natural radioactivity; c) the concept itself of visible light and the nature of the colours; d) the adaptability of the human eyes to the environment; e) the principles of the atomic structure as well as the basic concepts of energy quantization, including the photoelectric effect; f) the basic aspects of black-body radiation.

The Cenozoic Arabia–Iran continental collision was associated with emplacement of a large variety of magmatic rock types. This aspect is particularly evident in the Bijar-Qorveh area of NW Iran, where Miocene andesitic to rhyolitic rocks and Quaternary basic alkaline rocks crop out. The Miocene intermediate to acid products show radiogenic Sr and Pb isotopic compositions (87Sr/86Sri 0.70531–0.71109, 206Pb/204Pb 18.71–19.01, 207Pb/204Pb 15.66–15.73, 208Pb/204Pb 38.76–39.14), coupled with unradiogenic Nd isotopic ratios (143Nd/144Ndi 0.51223–0.51265). These characteristics, together with primitive mantle-normalised multielemental patterns resembling 'subduction-related' geochemical fingerprints, are considered ultimately derived from the Iranian plate mantle wedge, metasomatised during previous NE-directed Neothetyan Ocean subduction. The alkali-rich andesitic and dacitic rocks evidence both closed- and open-system differentiation, as typically observed for collisional settings in general. Both rock types display a high Sr/Y (37–100) and La/Yb (29–74) 'adakitic' signature that it is interpreted here with plagioclase (± amphibole) accumulation or melting of local mafic crustal rocks. Open-system processes involve recycling of crustal cumulates for pyroxene-rich andesite and biotite-rich dacite varieties and low-degree partial melting of the local crust for rhyolites. A radical change occurred during the Quaternary, when SiO2-understaturated to SiO2-saturated poorly evolved rocks (basanites, tephrites, alkaline and subalkaline basalts) were emplaced. The complete change of mantle sources suggests a phase of local extensional tectonics related with WNW-ESE right-transcurrent faults. The major oxide, as well as incompatible trace element and Sr-Nd-Pb isotopic fingerprint of these younger rocks is more akin to that of intraplate magmas, but still bearing some evidences for a variable contribution from a 'subduction-modified' mantle source. The NW-trend of increasing involvement of this subduction component is indicative of the strong tectonic control on magmatism. Additional lithotypes indicate the presence of open-system differentiation and remelting processes in the youngest phase of magmatic activity. [ABSTRACT FROM AUTHOR]