Secondary healed fissures in corundum are often filled with carbon dioxide, but usually in liquid form. On occasion we see it in both liquid and gaseous form. This series of four images shows liquid carbon dioxide with a gas bubble (the yellow area). As the heat of the microscope warms the specimen, the gas bubble shrinks and eventually disappears. The critical temperature at which the phase changes is 31.2°C. Solid carbon dioxide is what we know as “dry ice.” The existence of carbon dioxide inclusions in sapphire was first noted by David Brewster in 1826. He also noted the explosive nature of such inclusions, which burst at temperatures generally between 250–400°C.
Natural Sapphire • Sri Lanka (Ceylon) • Enhancements: None Detected (None) • Lighting Conditions: Fiber Optic: Diffuse Overhead
Photographer: Richard W. Hughes •
Image Number: A-002-5394-1 • Date Posted: 02 August 2017
Koivula, J.I. (1980) Carbon dioxide as a fluid inclusion. Gems & Gemology, Vol. 16, No. 12, pp. 386–390; RWHL*.
Brewster, D. (1826) On the existence of two new fluids in the cavities of minerals, which are immiscible, and possess remarkable physical properties. Transactions of the Royal Society of Edinburgh, Vol. 10, Part 1, pp. 1–41, 2 plates; RWHL.
Brewster, D. (1827) Notice respecting the existence of the new fluid in a large cavity in a specimen of sapphire. Edinburgh Journal of Science, Vol. 6, pp. 155–156; RWHL.