Tridymite

About: Tridymite is a research topic. Over the lifetime, 840 publications have been published within this topic receiving 14831 citations.

Influence of gamma radiation and action of neutrons on photoluminescence and the microhardness of barium silicate glass

Abstract: The influence of nanocrystals on the optical centers of barium silicate glass has been studied experimentally. It is found that, when glass is irradiated in the thermal column of an atomic reactor or in a gammasource 60Cо, the phase transformation of SiO2 nanocrystals (crystoballite into tridymite) and BaO into BaO2 and BaSiO3 occurs, which creates a brown coloration, reduction in the microhardness, and weakening of the luminescence intensity.

Production of silica brick

Abstract: PURPOSE:To obtain a tridymite-based silica brick contg. a small amt. of residual quartz and having improved creep resistance due to a small amt. of glass by adding specified amts. of a soda lime-silica melt and iron oxide to silica stock. CONSTITUTION:When silica stock based on silica is burnt produce a silica brick, the silica stock as principal stock is blended with 0.05-0.25wt.% powdery soda lime-silica melt having <=0.3mm particle size and a chemical compsn. consisting of, by weight, 70-75% SiO2, 5-13% CaO, 10-40% Na2O, 0.5-2% Al2O3 and 0.5-4% MgO and 0.1-1.0wt.% (expressed in terms of Fe2O3) iron oxide made of FeO.Fe2O3, Fe2O, Fe2O3 or Fe2O-Fe2O3 and having <=0.3mm particle size.

Crystalline silica minerals in air-borne pyroclastic materials

Abstract: Quartz is the most abundant, essential constituent of common volcanic rocks whereas tridymite and cristobalite occur in siliceous volcanic rocks. The mineralogy these minerals has been well established (DEER et at., 1963).

The effect of sulfur dioxide partial pressure on gas-slag-matte-tridymite equilibria in the Cu-Fe-O-S-Si system at 1200°C

Abstract: The gas-slag-matte-tridymite equilibria in the Cu–Fe–O–S–Si system at 1200°C have been experimentally studied An improved experimental technique was used, which includes high temperature equilibration of sulfide-oxide mixtures on silica substrates at p(SO) = 06 atm, preservation of the equilibrium phases by rapid quenching, and direct compositional analysis of the phases using microanalysis techniques The new data have enabled the effects of sulfur dioxide partial pressure between 01 and 06 atm on the equilibria to be accurately determined Whilst, for a given matte grade, the dissolved copper in slag is not sensitive to sulfur dioxide partial pressure, the Fe/SiO in slag in equilibrium with tridymite was found to increase with increasing p(SO) This latter observation has implications for fluxing practice in industrial copper smelting operations

Significance of tridymite distribution during cooling and vapor-phase alteration of ignimbrites

Abstract: Abstract Thick sequences of silicic ignimbrites contain complex emplacement and cooling histories, often masking contacts between ignimbrite flow packages. Mineralogical and textural variations in these sequences are primarily a function of emplacement temperature and cooling time. Here, we focus on the use of the silica polymorph tridymite to understand the association of vapor-phase crystallization and devitrification within ignimbrite flow packages. As opposed to the common occurrence of cristobalite, the restricted domains in which we observe tridymite may provide more relevant constraints for interpreting post-emplacement devitrification and vapor-phase alteration. This study examines sections through the Whakamaru (New Zealand), Bishop (U.S.A.), and Grey’s Landing (U.S.A.) ignimbrites by combining textural observations with measurements of density, groundmass crystallinity, and the distribution and proportion of tridymite to cristobalite. The rheomorphic Grey’s Landing ignimbrite represents a high-temperature end-member scenario, with widely distributed tridymite (up to 20%) resulting from a high-magmatic temperature and rapid devitrification in a low-porosity deposit. In the welded Whakamaru and Bishop ignimbrites, metastable tridymite (up to 13%) is concentrated along boundaries between flow packages. Here tridymite is interpreted to crystallize in transient permeable zones, forming during vapor-phase alteration prior to compaction, where upper denser-welded flow materials serve as vapor seals. Our results suggest that tridymite may link the initial cooling and welding history of ignimbrites to vapor-phase alteration and devitrification, and may serve as a potential mineralogical fingerprint of depositional contacts, important for consideration of lateral transport of fluids in geothermal reservoirs.