我国某细脉浸染型钼矿床内的淡红沸石及其成因

淡红沸石(Stellerite)是辉沸石族矿物之一种,曾在白令海峡中的苏联铜岛、美国阿拉斯加的朱诺、芬兰和苏联东外贝加尔的一些多金属矿床发现过。前人对淡红沸石着重进行了结晶学和热分析的研究,而对其地质产状和成因以及与有关矿化的关系相对少一些。到目前为止,我国还沒有对淡红沸石进行过报导。

STELLERITE AND ITS GENESIS IN A DISSEMINATED MOLYBDENUM DEPOSIT

Stellerite, in association with calcite, pennine, pyrite, quartz, molybdenite and chalcopyrite, occurs in the oligoclase granite-porphyry, which has undergone a faint hydrotherreal alteration （chorite-carbonate phase）. Stellerite is transparent and has a light salmon-colour. The crystal of stellerite is tabular in habit with perfect （010） and poor （100） cleavages. Specific gravity=2.152. Hardness=3.5±. Indices of refraction Ng=1.500, Np=1.488, Ng-Np=0.012. Biaxial negative. 2V=42. Negative elongation. Six crystals of stellerite have been examined on a two-circle goniometer, with the c-axis paralleling to the axis of the goniometer head. The crystals show p{111}, b{010} and m{110}. The axial ratio determined from the goniometric data is a:b:c=1.150:1:0.848. DTA curve of stellerite shows an endothermic reaction between 100℃ and 250℃; an exothermic reaction ranging from 400°to 500℃. Stellerite is soluble in hot HCl, HNO3 and H2SO4 （All in 1:1）, separating some gelatinous silica. A chemical analysis of pure material has been made. The formula calculated from the analysis of stellerite may be formulated as (K0.071Na0.186Ca1.071)1.328(Al2.321 Fe0.028³⁺Mn0.028)2.377Si6.614O18·6.95H2O. The relationships in texture between different minerals have been studied, and a paragenetic sequence may therefore be established: sericite→dickite→pennine→molybdenite→stellerite→calcite. Stellerite is an important mineral in the study of hydrothermal process and of the origin of mineral deposits, especially those of Mo, W and Cu in granodiorite rocks.