Perlite is a volcanic glass that, under thermal treatment, expands, producing a highly porous and lightweight granular material which finds application in the construction, horticulture, insulation and other industrial sectors. Proper control of the feed properties and the expansion conditions allows the production of purpose-oriented grades, while the primary evaluation of its appropriateness for use in each sector is performed by the proper characterization of relevant physical, thermal or/and mechanical properties. However, due to its extreme fineness, low density, and friability, most of the available characterization methods either fail in testing or provide erroneous results, while for certain properties of interest, a method is still missing. As a consequence, the way towards the evaluation of the material is rife with uncertainties, while a well-defined methodology for the characterization of the critical properties is of practical importance towards the establishment of a pathway for its proper analysis and assessment. This article presents the available methodology for determining the main properties of interest, i.e., the size and density, water repellency/absorption and oil absorption, the microstructural composition, crushing and abrasion resistance and isostatic crushing strength, and also sampling and size reduction processes. The issues raised by the application of existing methods are analyzed and discussed, ending up to a proper methodology for the characterization of each property, based on the long-term experience of the Perlite Institute. The study is supplemented by updated insights on ore genesis, physicochemical properties, mineralogical composition and the expansion mechanism, as background information for the sufficient comprehension of the nature and properties of perlite.

Due to the lack of rock samples directly from the deep part of the Moon, experiments and numerical simulation are effective methods to understand the early evolution of the Moon. Since the 1970s, the Lunar Magma Ocean (LMO) evolution model has been verified and modified by a large number of experimental petrology and geochemical work. However, the original composition of the Moon and the depth of its magma ocean, which are the two most critical parameters of LMO models remain controversial. The different lunar crust thickness estimated from lunar seismic data compared to that estimated from gravity data, the volatile content of lunar samples, and the widespread of Mg and Al-rich spinet (Cr (#) <5) discovered from interpreting the new remote sensing data affect our assessment on the starting composition and the depth of LMO, and the fractional crystallization process thereafter. In this paper, we review a series of high temperature and high pressure experimental petrology and experimental geochemistry results on the Moon's early evolution by focusing on: (1) The influence of refractory elements and volatile content of LMO's composition and its depth on the thickness of lunar crust and the Moon's mineral constitution formed through early differentiation. (2) The rationality of stability of high pressure mineral garnet deep inside lunar mantle and it effect on the distribution of trace elements during the evolution of lunar. (3) The petrogenesis of the Moon's special components, including volcanic glasses and Mg-suite, and their indication on the composition of the Moon's deep interior. (4) The constraint of lunar core composition on the Moon's material source, especially the abundance of trace elements. Based on the latest observation and the new analysis results of lunar samples, we evaluate the existing LMO evolution models and propose a LMO model with garnet as an important constituent mineral inside the Moon. We also discuss the necessary work need to be done to improve the new LMO model.

Lunar volcanic glasses associated with mare basalt magmatism experienced significant degree of degassing, and to retrieve their initial water contents requires data of water diffusivity. We carried out diffusion experiments at 0.5 GPa and 1703-1903 K in a piston cylinder apparatus for two synthesized lunar basaltic melts with compositions corresponding to Apollo green glass and yellow glass. The water diffusion profiles measured by FTIR spectroscopy yield water diffusivities 0.5-1 order of magnitude greater than those of terrestrial basaltic melts, which is attributed to the difference in melt polymerization and modest contribution from H-2 diffusion. However, hydroxyl (OH) is not only the dominant H species but is also inferred to be the major carrier of H in our experiments at oxygen fugacity estimated IW +/- 1 (IW: iron-wustite buffer). Modeling of previously reported profiles of volatile loss in an Apollo green glass bead using the new water diffusivity indicates an average cooling rate of 1-2 degrees C/s and an initial water content of 120-260 mu g/g. With the assumption of limited degassing before magma fragmentation, the lunar mantle source is inferred to contain 6-22 mu g/g H2O. The lunar interior appears to be less hydrous the Earth's interior but still contains a considerable amount of water. (C) 2019 Elsevier B.V. All rights reserved.

We report the solubility of water in Apollo 15 basaltic Yellow Glass and an iron-free basaltic analog composition at 1 atm and 1350 degrees C. We equilibrated melts in a 1-atm furnace with flowing H-2/CO2 gas mixtures that spanned similar to 8 orders of magnitude in fO(2) (from three orders of magnitude more reducing than the iron-wustite buffer, IW - 3.0, to IW 14.8) and similar to 4 orders of magnitude in pH(2)/pH(2)O (from 0.003 to 24). Based on Fourier transform infrared spectroscopy (FTIR), our quenched experimental glasses contain 69-425 ppm total water (by weight). Our results demonstrate that under the conditions of our experiments: (1) hydroxyl is the only H-bearing species detected by FTIR; (2) the solubility of water is proportional to the square root of pH(2)O in the furnace atmosphere and is independent of fO(2) and pH(2)/pH(2)O; (3) the solubility of water is very similar in both melt compositions; (4) the concentration of H-2 in our iron-free experiments is similar to 200 ppm C would be required for the vapor composition to be dominated by CO rather than H-2 at 65-75% vesicularity. (C) 2016 Elsevier Ltd. All rights reserved.

Moon Mineralogy Mapper spectroscopic observations are used to assess the mineralogy of five sites that have recently been proposed to include lunar dark mantle deposits (DMDs). Volcanic glasses have, for the first time, clearly been identified at the location of three of the proposed pyroclastic deposits. This is the first time that volcanic glasses have been identified at such a small scale on the lunar surface from remote sensing observations. Deposits at Birt E, Schluter, and Walther A appear to be glassy DMDs. Deposits at Birt E and Schluter show (1) morphological evidence suggesting a likely vent and (2) mineralogical evidence indicative of the presence of volcanic glasses. The Walther A deposits, although they show no morphological evidence of vents, have the spectroscopic characteristics diagnostic of volcanic glasses. The deposits of the Freundlich-Sharonov basin are separated in two areas: (1) the Buys-Ballot deposits lack mineralogical and morphological evidence and thus are found to be associated with mare volcanism not with DMDs and (2) the Anderson crater deposits, which do not exhibit glassy DMD signatures, but they appear to be associated with possible vent structures and so may be classifiable as DMDs. Finally, dark deposits near the crater Kopff are found to be associated with likely mare volcanism and not associated with DMDs. The spectral identification of volcanic glass seen in many of the potential DMDs is a strong indicator of their pyroclastic origin.