Abstract: Minerals of the stibniteantimonselite series, in close association with tiemannite, clausthalite, kullerudite, Sebearing stibioluzonite, native gold, quartz and barite, were discovered in the Laerma and Qiongmo gold deposits, western Qinling, China. Based on Se/(S+Se) ratios of microprobe analyses this binary system of stibniteantimonselite is quarterly divided into stibnite, selenium stibnite, sulfur antimonselite and antimonselite. Microhardness of the stibnite subseries (Sb=58.47%-73.81%,S=11.86%-28.76%,Se=0.00%-29.12%) and the antimonselite series (Sb=43.78%-59.13%,Se=29.20%-49.72%,S=0.00%-11.43%) is 101.26 and 103.00 kg/mm², respectively. Reflectivities of the series are (470 nm)Rg’=42.62%-47.62%,Rp’=30.83%-40.55%; (550 nm)Rg’=41.84%-46.75%,Rp’=31.48%-38.85%; (590 nm)Rg’=42.25%-46.63%,Rp’=30.73%-39.46%; (650 nm)Rg’=43.30%-46.48%,Rp’=30.01%-41.56%. Cell parameters obtained from two Sebearing stibnite samples are a=1.120 9-1.121 2 nm,b=1.129 9-1.130 3 nm,c=0.384 7-0.384 9 nm,respectively. As may be seen from the above data, the higher the Se concentration, the bigger the cell parameters.

Key words: stibnite, antimonselite, mineral series