An unconventional method for preparing monoclinic Sr-feldspar starting from a synthetic Na-A zeolite is presented. Accordingly, samples of Sr2+-exchanged zeolite A (Sr-A), containing a residual 5% content of Na+, were thermally treated at temperatures up to 1150 degrees C for times up to 24 h. Sr-A zeolitic structure breakdown, occurred at about 900 degrees C and followed by the crystallization of the hexagonal form of Sr-feldspar (Sr-hexacelsian) at about 950 degrees C, resulted in the final conversion, in 1 h at 1150 degrees C, of the original zeolitic material into a monoclinic polymorph of Sr-feldspar. Increasing the duration of the thermal treatment up to about 5 h gave rise to the crystallization of monoclinic Sr-celsian at only 1000 degrees C. (C) 2008 Elsevier B.V. All rights reserved.