﻿REPORT OF THE DIRECTOR I9IO 151 



1 have asked Mr David H. Newland, Assistant State Geologist and 

 an accepted expert on gypsum and its commercial values, to express 

 his judgment of the usefulness of these deposits so far as indicated 

 by the analyses given. Mr Newland says : 



The sample no. I, described as " compact gray, with red and 

 green mottles," is an impure material, containing only about 62 

 per cent of hydrated calcium sulfate or gypsum itself. There 

 seems to be a good deal of free silica or quartz in the sample, and 

 also clay, the latter reaching 10 per cent or a little more. The 

 percentages of iron oxid and carbonates are likewise high as com- 

 pared with the amounts found in most of the gypsum used for 

 calcined plasters. Rock of the grade indicated by this analysis 

 would have little or no commercial value. Owing to the high 

 iron content the calcined product would undoubtedly be dis- 

 colored, as it would also be inferior in setting properties by reason 

 of its low percentage of calcium sulfate. 



Sample no. 2, coarse crystalline, with alternating black and 

 white bands, according to the analyses contains about 93 per cent 

 of gypsum substance. The chief impurities are lime and mag- 

 nesia carbonates. These act, of course, as dilutents but would 

 not be detrimental to the use of the material for most purposes. 

 The iron content is fairly low and the burned product should be 

 a good white. The material compares well with the average rock 

 used for the manufacture of calcined plaster in this country, 

 though somewhat inferior to the highest grade of gypsum as rep- 

 resented, for example, in some of the western deposits. 



. Sample no. 3, darker than no. 2, with finer bands, has about 96 

 per cent of the hydrated sulfate. It differs from no. 2, chiefly in 

 the smaller percentage of lime carbonate, the difference being 

 made up by the increase in gypsum. The small percentage of 

 alumina, indicative of the presence of clay, is negligible. While 

 the iron is somewhat less in amount than in the preceding sam- 

 ple, there would probably be no essential variance of color be- 

 tween the calcined product of the two grades. The main feature 

 is the increased percentage of the gypsum, which adds by so 

 much to the commercial value of the rock. 



Soil. The soil of the islands is essentially residual. The islands 

 have never been subjected to glacial action. One find's on the sand 

 spits and on the lower rock platforms, especially of the northern 

 islands, plenty of ice-borne boulders, for the most part dropped 

 where they lie, and now glazed by the blown sand, but there has been 

 no disturbance of the soil by ice erosion. Hence the softer red rocks, 

 which are largely felspathic, have undergone deep decomposition in 

 place and, under the vegetable mould at the top, the soil extends 

 downward often for 5 or 6 feet carrying all the structure of the 



