- Flint glass
Flint glass is optical
glassthat has relatively high refractive indexand low Abbe number. Flint glasses are arbitrarily defined as having an Abbe number of 50 to 55 or less. The currently known flint glasses have refractive indices ranging between 1.45 and 2.00. A concave lens of flint glass is commonly combined with a convex lens of crown glass to produce an achromatic doublet lens because of their compensating optical properties.
With respect to glass, the term "flint" derives from the
flintnodules found in the chalk deposits of southeast England that were used as a source of high purity silica by George Ravenscroft, circa 1662, to produce a potash lead glassthat was the predecessor to English lead crystal.
Traditionally, flint glasses were
lead glasses containing around 4%–60% lead oxide; however, the manufacture and disposal of these glasses are sources of pollution. In many modern flint glasses, the lead can be replaced with other additives such as titanium dioxideand zirconium dioxidewithout significantly altering the optical properties of the glass.
Flint glass can be fashioned into
rhinestones which are used as diamond simulants.
Crown glass (optics)
*Kurkjian, Charles R. and Prindle, William R. (1998). Perspectives on the History of Glass Composition. "Journal of the American Ceramic Society", 81 (4), 795-813.
Wikimedia Foundation. 2010.