Some aspects of the thermal history of lunar glass

Cooper, AR, Varshney.Ak, Sarkar SK, Swift J, Yen F, Klein L.  1972.  Some aspects of the thermal history of lunar glass. Journal of the American Ceramic Society. 55:260-264.


Electron microprobe examination revealed that glassy lunar fragments had inclusions as well as boundaries between mineral glasses of different compositions. Glassy lunar spherules (40 to 60 μm in diameter) showed detectable heterogeneity less marked than that of the fragments. The room-temperature refractive indices and densities of the spherules are changed by heat-treating them at 500° to 7O0°C. The large increases (as much as 2% in density and 0.7% in index of refraction) are difficult to explain on the basis of classical glass-transition phenomena alone unless extremely rapid cooling rates are assumed. Further, the spherules darkened significantly when they were heated in air or a medium vacuum (∼10−5 mm Hg) above 625°C.