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Fluid inclusions found in ore stage authigenic quartz, carbonate, and albite at the Spar Lake deposit still record ore stage conditions despite post ore burial metamorphism at greater than 325 °C. Quartz overgrowth and carbonate cements were either synchronous with or slightly pre-ore, and albite was either synchronous with or post-ore; all are part of a zoned system of Middle Proterozoic Revett Formation sandstone cements that includes the ore sulfides. Ore-stage microtextures and microzonations are preserved in these and other ore stage cements. Ore stage fluid inclusions are <5/i in size and occur as isolated, 2-phase, liquid-vapor (L-V) inclusions with tiny gas bubbles or as 1-phase liquid (L) inclusions. The L inclusions may be metamorphically homogenized equivalents of the L Vs, or they may have been trapped at near ambient temperature. L V inclusions homogenize to liquid at a range of temperatures varying from 74 °C, in the fringing GALENA-CALCITE zone, to more than 175 °C in orebody BORNITE-CALCITE and CHALCOCITE-CHLORITE zones. No homogenization temperatures (T^'s) under 130 °C are found in the orebody, and no T^'s above 130 °C are found in the fringe GALENA-CALCITE zone. Th 's also decline from the orebody across the CHALCOPYRITE-ANKERITE zone, so that this zone could not have been a feeder. Instead, it was an ore stage, thermal equivalent in pre ore hematitic sandstone of the CHALCOPYRITE-CALCITE and GALENA-CALCITE zones that formed in pre ore pyritic sandstone. Ore fluids must have fed from below, then spread along permeable layers. Four L-V inclusions in authigenic albite from a newly described albitic zone have T^'s no less than 230 °C. The ALBITE zone lies on a projection of mineral zoning towards a hypothetical ore fluid source from both the CHALCOPYRITE-ANKERITE and CHALCOCITE-CHLORITE zones. Anomalously low copper contents, the mineral zonation constraints, and the higher temperatures strongly suggest that the ALBITE zone was a major source of metals for Revetthosted deposits. INTRODUCTION The Spar Lake deposit has been described by Hayes and Einaudi (1986) as a peneconcordant strata bound copper-silver deposit of the type commonly associated with red beds. Its sulfide mineral zonation is directly comparable with that of deposits like White Pine, Mich., the Kupferschiefer in northern Europe, and the Zambian Copperbelt. It is even more directly comparable with sandstone-hosted Russian deposits of the Udokansk and Dzhezkazkan ore fields. It shares petrographic features to a truly remarkable degree with descriptions of Dzhezkazkan ores (Gablina and Tsepin, 1975). Before mining began in 1981, the Troy orebody in the Spar Lake deposit contained 64 million tons of 0.74 percent Cu and 1.58 oz/ton (Troy) Ag. The Spar Lake deposit is located 13 miles south of the town of Troy near Montana's western border (fig. 1). The Spar Lake deposit is hosted by the upper member of the Revett Formation, Ravalli Group, Middle Proterozoic Belt Supergroup (fig. 2). It is

A preliminary study of thermometry and metal sources of the Spar Lake strata-bound copper-silver deposit, Belt Supergroup, Montana