NO. 2060. WOLFRAMITE, BERAVNITE, AND AXINITE— WHERRY. 503 



0.2250 gram heated on the steam bath with 10 grams tartaric acid 

 dissolved in water, for two days. The amount of powder was seen to 

 gradually decrease, and that remaining at the end of thisperiod weighed 

 only 0.0302 gram, representing thus only about 15 per cent of the origi- 

 nal material. This would no doubt have dissolved completely had it 

 been finely enough powdered, or had the heating been continued 

 longer, so it is evident that scheeUte is essentially soluble in tartaric 

 acid. This reagent therefore can not be used to differentiate scheelite 

 from calcite as an impurity in woKramite, but in the present case the 

 failure to obtain an alkaline reaction on ignition seems clear evidence 

 of the absence of calcite, so the calcium has all been regarded as in the 

 scheelite form. As noted in the description of the mineral, a yellowish 

 powder is visible in some cracks on the specimen; although every- 

 thing of this sort was carefully removed from the material used for 

 analysis, the presence of invisible cracks along which incipient altera- 

 tion by calcium-bearing solutions has occurred is quite within the 

 range of possibility. 



Tlie tartaric acid dissolved from the woKramite 4.16 per cent of 

 tungsten trioxide. Tlie 0.82 per cent of calcium oxide found would be 

 united with only 3.40 per cent, if in the form of scheelite, so that 0.76 

 per cent tungsten trioxide remains to be accounted for. But 0.90 per 

 cent ferric oxide and 0.07 manganous oxide were also found to be 

 dissolved. The manganous oxide would take 0.23 tungsten triox- 

 ide, leaving 0.53 which was united with ferrous oxide. The amount of 

 ferrous oxide corresponding would be, however, only 0.17 per cent 

 (0.20 as ferric oxide), which, subtracted from the total ferric oxide 

 found, leaves 0.70 free ferric oxide wliich was dissolved by the tartaric 

 acid. This, which is perhaps present as limonite, has been listed 

 separately in the analysis, the equivalent amount of feri'ous oxide, 

 0.63 per cent, having been subtracted from the total ferrous oxide 

 found. But on calculating the mineral composition of the original 

 material, following Mr. Hess's plan of assigning the tungsten first to 

 the manganese, calcium, magnesium, etc.,* a total excess of ferric 

 oxide of 2.2 per cent was found. Since the form of the remauiing 1.5 

 per cent of this is indeterminate, it has been necessary to include it 

 with the ferrous oxide, although it may be present as a ferric oxide 

 insoluble in tartaric acid, perhaps hematite, or possibly in solid 

 solution (see below). Mr. Hess ^ has found such an excess of iron to 

 be very frequent in wolframite. 



No. 2 was fused with sodium carbonate at as low a temperature as 

 possible, to prevent alloying of any of the copper with the platinum 

 crucible, and then, when the oxides insoluble in water were dissolved 

 in acid, the copper was first precipitated by hydrogen" sulphide before 

 the determination of the iron and manganese, and weighed as oxide, 



1 U. S. Geol. Surv., Bull. 583, 1914, p. 21. * Idem, p. 38. 



