The analysis indicates a fairly fusible composition and the color when fused is above criticism as is the case with practically all of the Maine feldspars when properly cleaned of their associated ferromagnesium impurities. This feldspar deforms between 1,270° and 1,285° C., being slightly more fusible than Seger cone 8, it does not, however, become distorted in the early stages of fusion as might be expected from its calcium content. It fuses to an opaque white glass.

PROPERTIES IN STANDARD PORCELAIN MIXTURE.

A standard mixture of this feldspar vitrifies at 1,270° C. and shows slight warpage at 1,330° C. The color is equal to that of the standard trial. Fired at 1,330° the product has a total shrinkage of 14.6 per cent, a cream-white tint, and a translucency of 0.615. Under the raw-lead and fritted glazes the color is unaltered.

a

There is an old abandoned quarry (3) at Edgecomb, 24 miles from the New Castle Township line and 4 miles southeast of Wiscasset. This deposit contains considerable impure pegmatite, due to the contamination of small biotite crystals, but also contains considerable commercial pegmatite, which is exposed in a well-defined part of the dike, 25 to 50 feet wide, and cleared of overburden for a distance of 100 feet. The same dike is exposed at various places of uncertain width for a distance of about 500 feet north. The dike is almost vertical. At the time of visiting an opening about 25 feet deep had been made for the recovery of mica of the muscovite variety, which occurs throughout the dike. The pegmatite contains small lenses of massive white quartz and some beryl in the parts rich in feldspar. The feldspar in the part of this dike not seriously contaminated with biotite mica was sampled and found to be of a very good quality but of a rather soft type, its deformation range being from 1,255° to 1,260° C. It fuses to an enamel-like glass and entirely loses its shape at 1,270° C.

a For a description of this deposit see Bastin, E. S., Economic geology of the feldspar deposits of the United States: U. S. Geol. Survey Bull. 420, 1910, pp. 27 and 28.

PROPERTIES IN THE STANDARD PORCELAIN MIXTURE.

The standard porcelain mixture of this feldspar vitrifies at 1,260° C. and shows warping at 1,290° C. Its color is hardly equal to that of the standard trial. Fired at 1,290° C. it has a cream tint by transmitted light and a translucency of 0.667, and a total shrinkage of 14.6 per cent. The color is unaltered under either raw-lead or fritted glaze.

The Hull property (4) is on the east side of Sheepscot River, 4 miles south of Wiscasset, in the town of Edgecomb. This dike follows a ridge along the east side of the river, its height varying from sea level at high tide to 200 feet above sea level. The pegmatite does not seem to be so clean at the higher points but the material exposed there may be capping. Pegmatite of excellent quality is exposed at a number of places, but no development work has been done, and hence no estimate of quantity or uniformity can be made.

Samples of the clean pegmatite have a deformation range of 1,275° to 1,290° C. and fuse to a semitransparent mass free from color.

SAGADAHOC COUNTY.

GEORGETOWN. NOBLE AND SMITH PROSPECTS.

On Georgetown Peninsula, due east of the Golding quarry, is a dike of pegmatite, which may be traced over a considerable distance. Two openings (5 and 6) have been made, but no feldspar has been shipped. The feldspar exposed is microcline pegmatite with a small content of impurity, chiefly biotite.

Samples of the feldspar show a deformation range of 1,278° to 1,290° C. and fuse to a translucent glass free from tint.

PROPERTIES IN STANDARD PORCELAIN MIXTURE.

The standard porcelain mixture of this feldspar vitrifies at 1,280° and at 1,330° shows no warpage. Fired at 1,330° C. it has a total shrinkage of 14.3 per cent, a cream color by transmitted light, and a translucency of 0.640. The color is unaltered under the raw-lead and fritted glazes.

The Alfred Graves quarry (7) 2 miles north of Cathance station. At the time of inspection this property had been opened by a pit about 30 feet wide, 40 feet long, and 10 to 15 feet deep. A dike of varying width is exposed in places for at least 100 feet along the strike northwest and southeast of the pit. The dike reaches a maximum width of 70 feet in some places, but froin surface indications its quality varies greatly. The overburden varies from one-half to 3 feet in thickness. Biotite occurs in considerable quantity in some parts of the dike, but in other parts is almost entirely absent. Beryl

is present locally, but not in sufficient quantity to constitute a menace. About 500 tons of commercial pegmatite has been mined and shipped from this property, which shows indications of much more feldspar of pottery grade. The deposit lies nearly flat, and a band of coarse, impure granite, encountered at a depth of 10 to 15 feet, is reported as continuing through to the other side of the sill, but no prospect holes or other evidence is available to substantiate this claim.

Samples of this feldspar show a deformation range of 1,265° to 1,280° C. and fuse to a semitransparent mass free from tint.

PROPERTIES IN STANDARD PORCELAIN MIXTURE.

In the standard mixture the feldspar produces vitrification at 1,280° C. and at 1,330° C. shows no warpage. The color is the same as that of the standard trial. Fired at 1,330° C. the mixture has a total shrinkage of 14.3 per cent, is cream white by transmitted light, and has a translucency of 0.645. The color is unaltered under the rawlead and fritted glazes.

The Maine quarry (8) is 2 miles north of Cathance station, on property adjoining on the south of the Alfred Graves property. This deposit is probably a continuation of the dike opened at the Graves quarry but dips more than on the Graves property. This dike varies widely in its structure, and much material high in impurity must be handled in the removal of the merchantable pegmatite. The dike dips under a ridge and the increase in thickness of overburden which must be removed has prevented very deep quarrying. The pegmatite part of the dike averages about 12 feet in width. The feldspar has a deformation range of 1,265° to 1,280° C. and fuses to a semitransparent mass free from tint.

PROPERTIES IN STANDARD PORCELAIN MIXTURE.

In the standard porcelain mixture this feldspar produces vitrification at 1,280° and no warping is evident at 1,330° C. Fired at 1,330° C., the total shrinkage is 14.0 per cent, the color by transmitted light is cream white, and the translucency is 0.650. The color is unaltered under the raw-lead and fritted glazes.

CATHANCE.

MAINE GRAPHIC GRANITE QUARRY.

This deposit (9) is 24 miles northwest of Cathance and is part of the dike worked at the large Trenton quarry one-half mile north. At the time of visiting a face 60 feet wide and 60 feet high, worked in two benches, was exposed. The material exposed is a good grade of graphic granite, but contains both black and white mica, and all of it has to be cobbed or sorted before it is sent to the mill. The quality of the feldspar is practically the same as that of the potash feldspar being mined at the Trenton quarry, although the structure of the

4492°-Bull. 92—16- -8

dike at this north exposure is more irregular and requires more careful mining than seems to have been necessary in working the older and larger opening.

A sample of the feldspar of this dike had a deformation range of 1,265° to 1,280° C. The fused product is a semitransparent mass free from tint.

PROPERTIES IN STANDARD PORCELAIN MIXTURE.

A standard mixture of the feldspar vitrifies at 1,270° and warps slightly at 1,330° C. The total shrinkage when fired at 1,330° is 14 per cent. The color is cream white, and the translucency is 0.635. The color is not altered by the application of either the raw-lead or the fritted glazes.

The Trenton quarry a (10), 2 miles northwest of Cathance, is one of the oldest feldspar operations in Maine and represents the largest production in the New England States. The quarry, which is about three-fourths mile west of the highway, consists of a series of open cuts ranging from 15 to 60 feet in height of face exposed and in some places is 200 feet wide. This deposit has been worked out for a distance of 200 yards and the indications are that it continues for a considerable distance to the north, which is the direction of the strike of the dike. The deposit mined has consisted chiefly of a rich graphic granite and coarse pegmatite, with numerous lenses of sugar quartz and pure feldspar that in some places is potash feldspar and in other places soda feldspar. The soda feldspar is more or less broken by weathering, presenting a chalky appearance, but the potash feldspar seems to be still unweathered.

Samples of the potash feldspar were tested and showed a deformation range of 1,265° to 1,280° C. The color is an excellent white and the standard porcelain body in which this material is used shows a shrinkage of 14.6 per cent and a translucency of 0.667.

The soda feldspar deforms only at a very high temperature, owing to the fact that the weathering has removed some of the alkali, leaving a residue of semikaolinized material. This soda feldspar has never been used by the operating company as a commercial product, but a test of this material in porcelain bodies shows that it has a shrinkage of 13.4 per cent and a translucency of 0.620, which indicates that it would be valuable fluxing material for many purposes.

b

The W. G. Willis quarry (11) is 1 mile west of Cathance. This property is south of the Trenton quarry and is apparently a continuation of this same dike or at least consists of stringers from this

a See Bastin, E. S., Economic geology of the feldspar deposits of the United States: U. S. Geol. Survey Bull. 420, 1910, pp. 38-39.

b Bastin, E. S., Op. cit., pp. 37-38.

dike. The mass is not so uniform as the main dike, but contains many large lenses of pure potash feldspar, the rest of it being an excellent grade of graphic granite. The opening of this quarry is in the center of a large flat plateau, and at the time of the writer's visit the quarry was filled with water to a considerable depth, making a satisfactory examination of this deposit impossible. The difficulty of operation has prevented this property being worked recently, but the feldspar mined was regarded as of excellent quality and was all bought and used by a local company.

The results of an analysis of a sample of this feldspar are as follows:

Results of analysis of potash feldspar from W. G. Willis quarry.

The old Golding quarry (12) is 1 mile west of Cathance station and adjoins the old W. G. Willis quarry on the south. This property was worked in former years when only the pure feldspar was removed, and hence much high-grade graphic granite is left and also many small dikes, which were formerly considered too small to justify quarrying. The structure and the strike of the deposit indicates that it is a continuation of the dike worked at the Maine, Trenton, and W. G. Willis quarries.

The new W. G. Willis quarry (13) is located on the same dike as the Trenton quarry, the old Golding quarry, and the old W. G. Willis quarry, and is due south from them. This quarry has the advantage of being near the southern slope of the hill, and hence the problem of drainage, which is the great handicap in the old W. G. Willis quarry, is not encountered here. The dike here, like all other exposures on this strike, varies widely but contains much pure feldspar and also much high-grade pegmatite and graphic granite. The muscovite, biotite, and beryl present in this part of the dike are all so coarsely crystalline that they can be easily eliminated by rough