Estimation of the Al,Si distribution of feldspars from the lattice translations Tr[110] and Tr[110]

A method is proposed to estimate the Al,Si distribution of alkali feldspars from two lattice translations, called Tr110] and Tr1¯10], which are the repeat distances in the 110] and 1¯10] directions. The Al content t₁0 of the T₁0 tetrahedral site is estimated from Tr1¯10], whereas Tr110] measures t₁m, the Al content of the T₁m site. In order to simplify the estimation procedure, the line separation =2 (131)-2 (1¯31) is given as a function of t₁0 and t₁0-t₁m.