The Marble Deposits, By E. F. Burchard.
Marble and Orr islands.
General Features.
“The most extensive developments of marble in southeastern Alaska are in the northwestern part of Marble Island, one of the larger islands in Davidson Inlet, on which marble was first discovered in 1899. Quarrying has been begun on Orr Island, just across the narrow inlet from Marble Island.
“Marble Island extends about 3 miles from east to west and about 4 miles from north to south. Its surface is densely wooded and is generally of moderate relief, the highest point noted by the Coast and Geodetic Survey being 1,528 feet above sea level. According to the Wrights,* the rocks of both Marble and Orr islands are classified as limestone and other sedimentary rocks, together with schists and volcanic tuffs, all of Paleozoic age. Much of the limestone in this area has been metamorphosed to a high-grade marble.
(* Footnote 1, page 66: Wright, F. E. and C. W. The Ketchikan and Wrangell mining districts, Alaska : U. S. Geol. Survey Bull. 347, pl. 1, 1908.)
Vermont Marble Co.’s Properties.
“Certain marble claims that were located in the northwestern part of Marble Island in 1903 have been purchased by the Vermont Marble Co., which has opened large quarries (No. 33) and built a small village named Tokeen. The total area held by the company aggregates 703 ¼ acres, according to the plat of mineral survey No. 927, made by L. D. Ryus, deputy mineral surveyor of Ketchikan. (See fig. 3.)
| Figure 3. Sketch map showing claims of Vermont Marble Co. on Marble Island (Alaska). (pp. 66) |  |
“Blue-black limestone. – The marble in the main quarry is massive and has yielded no fossils except crinoid buttons, but it overlies thin-bedded blue-black limestone which has yielded fossils of probable Silurian age, consisting of Merestina sp., Clorinda sp., Conocardium sp., Trochonema sp., Favosites sp., and Cyclonema sp., as determined by Edwin Kirk. of the United States Geological Survey.
“Southwest from the Tokeen wharf, along the shore of the island, an alternation of limestone beds, intrusive rocks, and marble occurs, but the blue-black limestone crops out around the cove in which the wharf is situated, and near the company’s office a small area has been stripped and several blocks of the stone have been taken out. The rock is fine grained and dense but is much fractured and jointed. The openings have been cemented with white calcite. The beds range from 1 foot or less to 3 feet in thickness but on weathering separate into thin layers 1 ½ to 5 inches thick. (See Pl. X, A.) The joints separate the rock in places into small blocks only 1 inch to 3 or 4 inches on an edge. The material takes a fine dark polish. (See Pl. VIII, B.) The rock is very brittle and breaks easily, not only along the calcite-filled joint cracks but also along the laminations parallel to the bedding planes. Probably most of the surface material will have to be rejected, but at greater depth the joint cracks appear to become fewer and the rock tougher. The white calcite streaks that intersect the dark surface produce very attractive effects in the polished stone and it was expected that the material would be quarried and marketed as ‘black marble.’
| Pl. VIII. B. Fine-grained black marble (blue-black limestone) from Vermont Marble Co.’s property, Tokeen, Marble Island (Alaska). (pp. 50) |  |
| Pl. X. A. Fossiliferous blue-black limestone beds in tramway cut 250 feet from the wharf, Tokeen (Alaska). (pp. 66) |  |
“T. N. Dale examined a thin section of this blue-black limestone and found that it consists of calcite, mostly untwinned, measuring with the micrometer 0.009 to 0.094 millimeter, but mostly 0.02 to 0.047 millimeter, and averaging probably about 0.05 millimeter, and is therefore to be classified as of fine grain. The microscope reveals sparse minute opaque specks, probably carbonaceous material, and some cubes of pyrite.
“The overburden consists of forest growth and decayed wood and mold 1 ½ to 3 feet thick. The rocks dip 38° - 40° NE., and the edges of their tilted beds have been cut by solution into a very irregular surface. The tramway from the wharf to the marble quarry passes the opening on the blue-black limestone, so that the material can be handled with a minimum of expense.
“White and veined marble. – Eastward from Tokeen the blue-black limestone passes beneath the deposit of white marble, which extends to and probably far beyond a small bight on the north side of Marble Island, 400 feet from the quarry. The belt of marble and dark limestone is probably 2,500 feet or more in width, and it extends southeastward into the interior of the island for a much greater distance – possibly nearly white with dark-gray and black veins to light-gray and grayish-blue shades. The grain is medium fine and fairly uniform. The marble having dark veins on a white background is very much in demand at present for interior decoration. Blocks are sawed into slabs, which may be matched so as to form certain nearly symmetrical patterns. Such slabs have been used in a large number of buildings near the Pacific coast. (See ‘Uses of Alaska marble,’ pp. 110-112 and Pls. XVI (p. 78), XXIII (p. 92), XXIV (p. 93), and XXV (p. 94).)
“Thin sections of the marble from Tokeen were studied microscopically by T. N. Dale. A section of the white marble showed a grain diameter of 0.07 to 1.5 millimeters, mostly 0.52 to 0.2 millimeter, with an estimated average diameter of 0.31 millimeter, falling within the limits of medium grain. the texture is very uneven. One section is crossed by a band of very fine untwinned dolomite (?) along which shearing has taken place. (See Pl. VI, B.) A section of the veined white and gray marble, which showed a very uneven texture, includes parts that are extremely fine and parts that are extremely coarse, but in most of the section the grain diameter ranges from 0.025 to 0.625 millimeter, mostly 0.1 to 0.375 millimeter. The Rosiwal measurements gave an average grain diameter of 0.0051 inch, or 0.13 millimeter. The grade is therefore, in general, medium. The rock shows streaks of very fine, untwinned magnesian calcite grains with graphite. A large grain of pyrite 0.4 millimeter in diameter was noted.
“The following determinations made by R. K. Bailey show that the veined marble contains considerable magnesia:
Analyses of white and veined marble from Tokeen.
Insoluble matter – (white) 0.01 (Veined) 0.20
Calcium carbonate (CaCO3) – (White) 99.51 – (Veined) 81.90
Magnesium carbonate (MgCO3) – (White).94 – (Veined) 14.93
“The marble appears to be wholly metamorphosed. The material is massive and shows no indication of its original bedding, but it is much jointed and fractured and within 10 to 20 feet of the surface is rather soft. The joint planes cut the deposit at many angles but may perhaps be referred to several systems, the two principal ones striking about N. 50° E. and N. 40° W. The dips of the joint planes are likewise at many angles, and the spacing of the joints is variable, ranging from a few inches to 10 feet or more. In some places parallel joints, or ‘headings,’ are rather close together, rendering it impossible to obtain blocks large enough for shipment, but elsewhere blocks 4 by 4 by 10 feet free from cracks may be easily obtained. Wedge-shaped blocks that are completely separated from the surrounding mass by smooth joint planes are occasionally encountered in quarrying. Near the northeast side of the main quarry the marble is cut by a dike of altered andesite porphyry, 8 to 16 inches thick, containing much pyrite and dipping 17° - 25° NE. (See Pl. XI, A.).
| Pl. XI. A. Andesite porphyry dike about 1 foot thick cutting marble beds on west side of Vermont Marble Co.’s Quarry, Tokeen (Alaska). |  |
“The jointed structure of the marble is the most serious hindrance to its profitable exploitation. It is to be expected that joint cracks should be present at the surface and that surface water should descend along these cracks, enlarging them, softening the marble, and oxidizing it to a faint yellowish hue, but according to experience in many other regions it might be expected that at depths of 40 to 60 feet the joint cracks would disappear and the marble become solid. To that depth quarried in 1912 (60 feet), however, it showed joint cracks in places (Pl. XI, B), and it may be possible that the widespread volcanism to which the Pacific coast of northwestern North America has been subjected has disturbed the rocks generally to much greater depths than in other marble-quarrying regions.
| Pl. XI. B. Face of marble at depth of about 50 feet in Vermont Marble Co.’s quarry at Tokeen (Alaska). |  |
“The white marble was also analyzed in the chemical laboratory of the Bureau of Standards, with the following results:
Chemical Analysis of white marble from Tokeen.
Iron oxide (Fe2O3) – Trace
Alumina (Al2O3) – 0.14
Lime (CaO) – 55.80
Magnesia (MgO) -.47
Sulphur trioxide (SO3) – Trace.
Loss – 43.77
Carbon dioxide (CO2) – 43.86
Insoluble residue -.26
Hydrogen sulphides (H2S) – Not detected.
Sample has 99.5 per cent CaCO3.
“The following physical tests were made for the Geographical Survey by the Bureau of Standards on a representative sample of the veined marble from Tokeen. The compression tests show that this marble possesses slightly higher compressive strength than some of the best-known Vermont marbles.*
(* Footnote 1, page 70: “Marble from South Dorset: Average compressive strength per square inch, on bed, 11,300 pounds; on edge, 9,100 pounds. Marble from West Rutland: Compressive strength per square inch, ‘Extra dark blue,’ 13,639 pounds; ‘ Rutland Italian,’ 14,068 pounds; ‘Rutland statuary,’ 11,525 pounds. Dale, T. N., the commercial marbles of western Vermont: U. S. Geol. Survey Bull. 521, pp. 101, 121, 1912.”)
Physical tests of marble from Tokeen, Alaska. (pp. 70)
“Quarries. – The main quarry operated by the Vermont Marble Co. on Marble Island in 1912 is about 900 feet northeast of the shore of the small cove at the northwest corner of the island, at an altitude of about 15 feet above the wharf. In places bare knobs of marble are exposed in the vicinity of the quarry, but the surface of the marble, which is very irregular (Pl. X, B) as a result of solution and erosion, is generally covered by 1 ½ to 3 feet in decayed wood and mold. In places the roots of trees have followed the crevices in the rock to depths of 5 to 6 feet. Trees and stumps are removed by derricks, and the soft mold by hand. The first small opening (Pl. XII, A) was abandoned at a depth of about 20 feet on account of several joint cracks 1 to 6 inches or more apart in the northwest end of the cut. These joints dip steeply toward the north, and the quarrying was shifted far enough northwest to avoid them for a time. This dip, however, brings them back into the quarried area at a depth of about 50 feet, and at 60 feet they are apparently about as numerous as at the surface.
| Plate X. B. Stripping operations of Vermont Marble Co., showing surface of weathered marble, Tokeen (Alaska). |  |
| Plate XII. A. First quarry opening, Vermont Marble Co., Tokeen (Alaska). (pp. 70) |  |
“In September, 1912, the top of the quarry opening measured roughly 90 by 100 feet, and the depth ranged from 10 to 60 feet. About one-half of the area had been quarried to the maximum depth. Methods of quarrying commonly in use at well-known marble quarries in the Eastern States are employed. ( See Pl. XIII.) The equipment in the main quarry consisted of the necessary drills, seven Sullivan single channeling machines, four gadders and pumps, all operated by steam power generated by a 125-horsepower boiler near the quarry, and a complete machine shop. The blocks of marble are lifted from the quarry by a 25-ton derrick and are carried to the wharf (Pl. XII, B) on flat cars running on a standard-gage track. The loaded cars move by gravity and are drawn back to the quarry by a 7/16-inch steel cable. Waste rock is also trammed down to the wharf and dumped into the water alongside the pier. Deep water is reached by a pier about 150 feet long. A 25-ton stiff-leg derrick for unloading cars and loading marble on boats is operated by a small steam boiler on the shore near the wharf.
| Plate XIII. A. Southwest corner showing stairway. Vermont Marble Co.’s Quarry, Tokeen (Alaska). (pp. 70) |  |
| Plate XIII. B. Lowest Floor. Vermont Marble Co.’s Quarry (Alaska). |  |
| Plate XII. B. Wharf and water front of Vermont Marble Co.’s property, Tokeen (Alaska). View shows derrick moving blocks of marble. The pile of rock in the water at the right of the wharf is waste marble. |  |
| Plate XVI. Panel of Brecciated marble from Tokeen, formed by matching slabs sawed from same block (Tokeen, Alaska). |  |
“In September, 1912, a space of 1 ½ acres about 375 feet southeast of the main quarry was being cleared for a new quarry. (See Pl. X, B.) The highest knobs of marble rise here to about 35 feet above the level of the wharf. The marble at this new opening is chiefly white with bluish-gray to black veins and clouds similar to that at the first quarry, but the deposit contains more dark-veined stone. One dike of meta-andesite 1 ½ to 2 feet thick, striking N. 35° W. and dipping 78° SW., was noted. A full equipment (sic) had been installed, and in 1913 and 1914 active quarrying was carried on at this opening, two or three courses of stone having been removed. It is reported that below the surface, as far as quarried, the stone is fairly free from joints and fractures, and a good output of dark-veined marble seems assured.
“About 60 men were employed in connection with this plant in 1912. The men live in sanitary and comfortable dormitories, eat excellent fare at a commodious mess hall, enjoy generally favorable conditions under which to work, and show a high degree of efficiency. Quarrying is carried on for eight months or more each year. The winters are not severe, and operations probably can be carried on throughout most of the year when pipes from a reservoir are laid underground so that there shall be no danger of interruptions by freezing of the water supply.
“Products. – Rough blocks 4 by 4 by 6 to 10 feet are shipped by freight steamers to the mill of the Vermont Marble Co., at Tacoma, Wash., where they are sawed, polished, turned, or planed for interior decoration. To save freight only perfect blocks are shipped, and therefore considerable material is wasted at the quarry. Some of the waste marble is trammed down to the wharf and used as filling. (See Pl. XII, B.) According to the absence or presence of joints the proportion of waste marble quarried may vary between 10 and 75 per cent. The marble for a foot or more on each side of most fractures is discolored and must be cut away. If a fracture crosses the block diagonally or near the middle, it may render the whole block worthless. If cheap power is developed, it might prove an economy to operate a small sawing plant at Tokeen in order to work the waste marble into slabs or building blocks.
“Other prospects. – The Vermont Marble Co. has prospected claims about 1 mile and 1 ½ miles south of Tokeen (No. 34). At one point a white marble of about the same texture as that at Tokeen, but somewhat shattered, is exposed in a small quarry at the base of a low bluff, where, it is reported, marble was obtained many years ago for making tombstones. The surface marble here has been softened by long exposure to atmospheric agencies, and none from any considerable depth was available.
“At a second place several variegated marbles have been exposed by prospect pits. The most characteristic varieties are colored light to dark green, bluish, mottled light pink, and brownish gray. The mottled character is due to the presence of veins and nodules of fine-grained, dense calcareous material having a cherty appearance. The green varieties are veined with grayish green, darker than the body of the rock. The rock is massive and jointed and is cut by a thin dike of meta-andesite striking N. 40° W. The deposit was prospected by three or four drill holes, 60 to 94 feet deep, which showed that the green stone changed to gray or bluish within 15 to 25 feet from the surface. A small area was next stripped by hand, and two or three shallow pits were opened by a channeling machine, in the hope of developing a supply of desirable green marble. A wooden track on an incline was built from the test pits a short distance down to the water, in order to get out a few sample blocks of stone, and testing operations have been continued from time to time since 1912.
“Between these two prospects there is a beach about 1,600 feet in length, along the greater part of which marble beds are exposed. The marble is veined and is white to grayish. It is cut by several meta-diabase dikes 8 inches to 2 ½ feet thick, some of which are broken and distorted. One dike noted had been faulted and offset horizontally a few feet, but the marble that filled the space between the broken ends of the dike showed only a flowage structure without a definite fault plane. The intrusion of the dike and the deformation of the beds through which it passes probably proceeded the metamorphism that produced the marble.
“Thin sections of two samples of the variegated marble from the deposit 1 ½ miles south of Tokeen were examined by Messrs. Dale and Loughlin. The brownish-gray cherty-appearing material is of very irregular texture. The grain diameter of the finer matrix, which consists of untwined calcite, ranges from 0.025 to 0.075 millimeter, with an estimated average of 0.03 millimeter. The coarser calcitic part shows a grain diameter of 0.05 to 1.125 millimeters, mostly between 0.12 and 0.5, with an estimated average of 0.23 millimeter. Muscovite or phlogopite crystals reaching a length of 0.047 millimeter are widely disseminated. One grain of pyrite 0.7 millimeter in length was noted. A lens of dense dark granular material, cracked and veined with twinned calcite, appears in the section. The texture of the greenish marble was also found to be very irregular. The grain diameter of the finer matrix, most of which is probably untwined calcite, is 0.02 to 0.12, most of the prominent grains ranging from 0.05 to 0.07, with an estimated average of 0.03 millimeter. The grain diameter of the coarser part, which is calcitic, ranges between 0.12 and 0.87 millimeter, with an estimated average of 0.24 millimeter. Much pyrite and a light-brownish mica (biotite) are present throughout the section, and some dark-grayish, very fine grained bands, cracked and veined with calcite, are prominent. These bands contain much fine epidote, scarce hornblende, and possibly some quartz and other silicate minerals not easily susceptible of recrystallization, indicating that the rock stretched and fractured and the relatively pure carbonate rock recrystallized and ‘flowed’ into the stretch fractures.
“The following determinations by R. K. Bailey indicate that there may be some cherty material in the brownish-gray rock:
Analyses of brownish-gray marble from deposit 1 ½ miles south of Tokeen.
Insoluble matter – (Brown rock) 20.77 – (Green rock) 7.82
Calcium carbonate (CaCO3) – (Brown rock) 78.65 – (Green rock) 91.70
Magnesium carbonate (MgCO3) – (Brown rock) 1.87 – (Green rock) 1.21
“Limestone, slightly metamorphosed in places but generally a fine-grained bluish rock much fractured and seamed with calcite, alternating with graywacke, forms the coast line around most of the west and south sides of Marble Island. A considerable area of true marble, however, occurs along the middle of the east side of the island and on the west side of Orr Island, which is separated by a narrow channel from Marble Island.
| Plate XXIII. Entrance to Yeon Building, Portland, Oregon, decorated with Tokeen Marble (Alaska). Note the matched panels produced by sawing slabs of clouded marble. |  |
| Plate XXIV. Corridor, University of Utah, Salt Lake City, Utah, decorated with Tokeen marble (Tokeen, Alaska). |  |
| Plate XXV. Lobby of Isaacs Building, Los Angeles, Calif.; floors, stairs, and walls of Tokeen marble (Tokeen, Alaska). |  |
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