Amicite, a new natural zeolite

A new natural zeolite from Hoewenegg in Hegau (Germany) is described. Amicite [72283-44-4] has a space group I2 with a = 10.226, b = 10.422, c = 9.884 Å, and β = 88°19'. Unit-cell content K3.75Na3.61Ca0.05[Al7.86Si8.24O32].9.67 H2O results from electron microprobe and thermogravimetric analyses. On the basis of the structural topol., amicite is related to garronite and its ordered phase gismondine. The power pattern resembles that of synthetic zeolite Na-P. Amicite was found in the veins of a melilite-nephelinite rock and is assocd. with merlinoite and CaCO3.