Physicochemical or geochemical

• Nicol, E. R. , Lee, E. S., Murrow, P. J., (1985), Respirable Crystalline Silica in Ash Erupted from Galunggung Volcano, Indonesia, 1982, Atmospheric Environment, 19(7), 1027-1028, 10.1016/0004-6981(85)90185-4