I is for isinglass

Once commonly used in coal and wood-burning stoves, U.S. production of mica has all but ceased.

By Bill Langer

ˈī-zәn-glas (noun): two materials, both of which can occur in thin, relatively transparent sheets: (1) thin sheets of mica; (2) a gelatin made from fish bladders.

(Author’s note: This article is about mica, not fish guts. I am a geologist, not an ichthyologist.)

When I hear the term isinglass, I start singing ‘with isinglass curtains y’ can roll right down, in case there’s a change in the weather.’ Those of you who are Broadway stage or old movie buffs, or have kids who perform in high school plays, might recognize the lyrics from The Surrey With The Fringe On Top, a song from Rodgers and Hammerstein’s 1943 Broadway production and 1955 motion picture film, Oklahoma. The lyrics refer to oiled canvas side curtains with large isinglass (mica) inserts used on horse-drawn carriages and early automobiles. (Go ahead, hum a few bars.)

Mica mining in the United States began in 1805 in New Hampshire pegmatites. Some mines produced sheets over 3 feet wide.