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The crystal structure of the new mineral voggite, Na2Zr(PO4)(CO3)(OH).2H20 , from the Francon quarry, Montreal, Quebec, Canada, has been solved in order to determine the correct chemical formula, as conventional electron microprobe methods were found unreliable. The unit cell is monoclinic, I2/m, with a= 12.261(2), b = 6.561(1), c= 11.757(2)/~, 13= 116.19(2) ~ The structure consists of layers of edge-sharing Zr-O pentagonal bipyramids, separated by layers of Na-(O,H20) octahedra. The carbonate ion acts as a bidentate ligand in the Zr-O polyhedron, the third oxygen atom being bonded to the Na atom. The phosphate group is bonded to three different Zr atoms and to a Na atom. The Zr-O bond lengths vary from 2.067 to 2.283 (mean 2.140A), while Na-O are between 2.304 and 2.773, (or= 0.006/~, mean 2.480A). The carbonate and phosphate bonds are normal. It is inferred from the structure that the columns of octahedrally coordinated Na atoms can easily be broken apart when subjected to the heat generated by the electron microprobe beam, with the subsequent expulsion of water. This gives rise to 'mobile' Na atoms, which make quantitative electron microprobe analysis extremely difficult. The structure allows the 'liberated' Na atoms to move freely within planes parallel to (10T).

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Trichodermaspp. - The Cause of Green Mold on Polish Mushroom FarmsThe first reports concerning green mold on Polish mushroom farms are from 2002. In Europe and the United StatesTrichoderma harzianumwas initially described as a causative agent of the disease. However, soon two biotypes ofTrichoderma, Th2 in Europe and Th4 in America, were recognised as responsible for commercial losses and were designated as a new species namedT. aggressivum.Until now it has not been clear which species ofTrichodermaand which form of the species was a causative agent of the disease outbreak in Poland and what was the main source of infection. Therefore, studies were conducted on the composition of theTrichodermaspecies in Polish mushroom farms and in compost samples. The isolates were identified by phenotypic and microscopic studies. The classification of the strains recognised asT. aggressivumwas then confirmed by PCR methods. The aggressiveness ofTrichodermaspp., especiallyT. aggressivum, was estimated inin vitrostudies. The most frequently isolatedTrichodermaspp. were:T. harzianum, T. aggressivum, T. atrovirideandT. longibrachiatum.Using the technique of PCR, multiplex PCR and PCR-RAPD it was determined that 24 isolates from Polish mushroom farms belonged toT. aggressivumf.europeanum(Th2). However, a large variation between isolates indicated the possibility that Polish biotypes ofT. aggressivumwere different from those, which were found in western Europe. All isolates ofT. aggressivumwere highly pathogenic towardsAgaricus bisporus.