Variability of alpha/szlig Inversion Temperatures of Natural Quartz

The inversion temperature of quartz at atmospheric pressure is 573 C. This temperature shows some variability caused by source of quartz, particle sizes, heating rate and pressure ( nitrogen atmosphere). The differential thermal analysis ( DTA) of natural hydrothermal and pegmatite quartz indicate that, 1- the inversion temperatures of both natural pegmatite quartz and natural hydrothermal quartz with the same particle size ( 0.1 mm) and the same heating rate (10 C /min. ) are 582.14C and 582.4 C respectively with small differences ( ~0.3C - 0.5C).2- by changing the rate of heating from 10 C / min to 15 C /min, the inversion temperature of pegmatite quartz changed from 582.14 to 584.60 C and hydrothermal quartz temperature changed from 582.40 C to 585.10 C with relatively large differences ( ~ 2.46C 2.7 C).3- by increasing the particle size of pegmatite quartz to 1.0 mm. at heating rate 10 C / min, the inversion temperature increased to 587.0 C.4- by decreasing the particle size of pegmatite quartz to 0.05 mm at heating rate 10 C /min. , the inversion temperature disappeared.5-The hydrothermal quartz not show thermal activity above the inversion temperature but the pegmatite quartz has thermal activity above the inversion temperature.