are the chief impurities. This dike has been worked on a limited scale at a number of points and shows fair uniformity wherever opened.

The east dike is a widely varying mixture of potash feldspar pegmatite and soda feldspar pegmatite. It is much smaller in extent than the west dike and shows a structure similar to the gem bearing dikes of Maine. Much clevelandite is scattered through this dike, and black, pink, and green tourmaline are noted, although the tourmalines are all opaque and not of the gem quality. The albite parts of the deposits are of doubtful value, but the potash feldspar pegmatite, which is similar in both dikes, shows a good color and has a deformation range of 1,275° to 1,290° C.

PROPERTIES IN STANDARD PORCELAIN MIXTURE.

This feldspar, in the standard porcelain mixture, gives a vitrious product at 1,290° C. and shows no warpage at 1,330° C. The color is equal to that of the standard trial. At 1,330° C. the translucency is 0.680 and the total shrinkage is 13.9 per cent. The color is unaltered under either the raw-lead or the fritted glaze.

The Consolidated Feldspar quarry a (53) is located 3 miles east of Middletown, Conn., at an elevation of nearly 500 feet above the Connecticut River. The dike has been opened along a northeast face, showing a width of about 50 feet. The composition of the dike is decidedly variable. In many places it is remarkably free from impurity and shows considerable masses of pure buff feldspar of the potash variety; in others it is very fine-grained pegmatite with much mica and small garnets. The gradation is so pronounced, however, that no difficulty in sorting would be experienced.

The feldspar content of this dike was sampled and shows by chemical analysis the following composition:

It has a deformation range from 1,275° to 1,290° C. and fuses to a translucent mass free from tint.

a For a description of this deposit see Bastin, E. S., Economic geology of the feldspar deposits of the United States: Bull. 420, U. S. Geol. Survey, 1910, pp. 49-50.

PROPERTIES IN STANDARD PORCELAIN MIXTURE.

In the standard porcelain mixture this feldspar vitrifies at 1,280° C. and at 1,330° C. shows no evidence of warping. The color is equal to that of the standard trial and does not alter under either the raw lead or the fritted glaze. Fired at 1,330° C., the total shrinkage is 14.2 per cent and the translucency is 0.673 and the color cream white.

The Bidwell quarry (54) is located 24 miles south of Middletown, on Haddam Pike. The quarry was worked about 40 years ago, and recently has been reopened and worked for its pegmatite. The deposit consists of a dike which strikes due north and has been mined to a depth of 20 feet for a distance of about 200 feet. The material removed is reported to have been buff potash feldspar, but that now exposed in the walls and floor consists of about equal proportions of microcline and albite. This quarry should produce a considerable amount of mixed feldspar high in soda content and valuable for softening the feldspars high in potash. An average sample of the feldspar shows a deformation range of 1,265° to 1,275° C. and fuses to a semiopaque enamel of good white color.

PROPERTIES IN STANDARD PORCELAIN MIXTURE.

In the standard porcelain mixture this feldspar vitrifies at 1,270° C. and shows pronounced warping at 1,330° C. The color is a faint gray. Fired at 1,330° C. the shrinkage is 13.8 per cent and the translucency is 0.630 and the color is cream. The application of raw lead and fritted glazes intensifies slightly the gray tint of the unglazed porcelain.

The Hallberg deposit (55), 2 miles southeast of Middle Haddam village, does not differ materially from the one at the Middle Haddam quarry, except that gem minerals are absent. The dike is opened by a pit at its northeast terminus on an abrupt bluff of a hill. The width of the dike where exposed in this pit is about 20 feet, and a face about 20 feet high has been uncovered.

The pegmatite in this deposit was sampled and found to have a deformation temperature of from 1,270° to 1,285° C.

It fuses to a semitransparent glass with a faint blue tint.

PROPERTIES IN STANDARD PORCELAIN MIXTURE.

In the standard mixture the above feldspar vitrifies at 1,280° C. and at 1,330° C. a slight warpage is noted. Fired at 1,330° C., the total shrinkage is 14.5 per cent, the translucency is 0.657, and the color is cream. The porcelain shows a faint gray tint which is intensified by the application of both the raw lead and the fritted glaze.

MIDDLE HADDAM. MIDDLE HADDAM QUARRY.

The Middle Haddam quarry (56), 1 miles southeast of Middle Haddam village, consists of a number of small openings scattered over a territory comprising several hundred acres. The largest single operation consists of an opening in the west slope of a hill overlooking the Connecticut River and the dike where exposed seems to be about 40 feet wide and to have a general northeasterly strike. This deposit is about one-half of a mile from the river and the material is hauled to the face of an abrupt cliff and dumped into lighters moored below it. The product of the quarry is a granite pegmatite, practically no lenses of pure feldspar being observed. Crystals of muscovite of moderate size occur at frequent intervals, but few specimens of commercial value are noted. Black tourmaline and biotite are scattered through the deposit and require careful hand sorting to eliminate them. The occurrence of lepidolite and colored tourmaline are reported from this deposit, but none was observed at the time of its inspection. The cleaner parts of the pegmatite were sampled and found to have a deformation temperature of 1,270° to 1,285° C. When fused the feldspar is semitransparent and has a faint blue tint.

PROPERTIES IN STANDARD PORCELAIN MIXTURE.

In the standard porcelain mixture this feldspar vitrifies at 1,280° C., and at 1,330° C. warps slightly and has a faint gray tint. When fired at 1,330° C. the total shrinkage is 14 per cent and the translucency is 0.630 and the color is cream. Under the rawlead and fritted glazes the gray tint is somewhat intensified.

Haddam Neck quarry (57) is located on the east bank of the Connecticut River, opposite Haddam village. This deposit consists of a dike about 100 feet wide and has been worked for a distance of about 350 feet and to a depth of about 30 feet. The deposit contains a variable pegmatite with many inclosed masses of albite and small lenses of microcline; graphic granite was exposed in many parts of the quarry when visited. The pegmatite is mixed with micas, black tourmaline, garnet, and other minerals and many gems are reported as being found in this quarry. The feldspar is a buff microcline intergrown with albite of a white and pale-green color. Free from quartz, this feldspar shows a deformation range from 1,266° to 1,285° C., and when fused is semitransparent and has a good color.

PROPERTIES IN STANDARD PORCELAIN MIXTURE.

In the standard porcelain mixture this feldspar vitrifies at 1,280° C., and at 1,330° C. no warping is noted. The color is almost equal to that of the standard trial. Fired at 1,330° C. the total shrinkage is 14 per cent and the translucency is 0.637 and the color is cream white. The color is not altered under the raw-lead and fritted glazes.

a

The Bridgeport quarry is located about 1 miles south of Oxford, Conn. This quarry is an open pit about 150 by 100 feet in size and the deposit seems to be an isolated lens of pegmatite which apparently does not continue in either direction. The quarry has been abandoned some time and at the time of visiting was filled with water so that no estimate of what its content was, or what material the walls are, could be formed. The parts exposed above the water consist largely of a coarse pegmatite with isolated lenses of feldspar of widely varying color and structure. The quartz in this quarry is reported as having been rose quartz and massive white sugar quartz. The quantity of feldspar exposed is not sufficient to justify a statement regarding the probable quality of the feldspathic material of the deposit.

NEW YORK.

All the feldspar deposits investigated in New York are shown in Plate VI except those in Westchester County, which are shown in Plate V.

ESSEX COUNTY.

CROWN POINT. CROWN POINT QUARRY.

The Crown Point quarry (58) is 2 miles southwest of Crown Point and 1 mile west of Lake Champlain. The deposit is an expanded pegmatite dike, of widely varying composition, with a northeast strike. The dip is uncertain, but is almost vertical where exposed by quarrying for a width of about 40 feet.

The pegmatite is a coarse mixture of pearl-gray microcline and green plagioclaso with variable contents of quartz and leaves of biotite along the contact faces between the masses of microcline and plagioclase. In this quarry the central part of the dike contains more microcline than plagioclase, and along the walls the plagioclase appears to predominate. Along the west wall a hematite-red stain occurs on the faces of the microcline crystals, but does not penetrate the feldspar masses. The overburden varies from nothing to 4 feet and is a soil made up largely of weathered dike material.

The nature of the deposit would demand great care in selecting the feldspar if it were to be marketed for ceramic uses. Many parts are so mixed with biotite that cleaning would be impracticable, but at least one-third of this dike would justify cobbing for its microcline. The mining at present is for material to be used in the manufacture of roofing and for poultry grit, and for these purposes the run of the quarry can be used without cleaning of any impurity except the small

a For a description of this deposit see Bastin, E. S., Economic geology of the feldspar deposits of the United States: Bull. 420, U. S. Geol. Survey, 1910, pp. 53–54.

b See Bastin, E. S., Op. cit., pp. 54-55.