15 km south of St. Matthew Island. The actual name is Pinnacle Island. The hard part will be getting ashore. If you've read any sailing/climbing books like Tilman's Kerguelen Island adventures. Getting ashore is often the crux.
Probably volcanic choss. Looking through the records, I don't know that anybody has ever landed on Pinnacle Island although some say there are a few beaches where one might land is the swells were small. Seems to be surrounded by pack ice most of the time and bad weather almost always.
BERING SEA NATIONAL WILDLIFE REFUGE
By EDWARD H. COBB
The islands and offshore rocks that constitute the Bering Sea National Wildlife Refuge are made up of volcanic rocks and surficial deposits. No deposits of minerals subject to leasing under the mineral leasing laws or to location are known in the refuge.
The uninhabited islands that constitute the Bering Sea National Wildlife Refuge are near lat 60°30' N. and long 173° W. in the middle of the Bering Sea, more than 200 miles from the Alaska mainland and about 375 miles southwest of Nome, the closest city. Cape Chukotskiy, the nearest point on the Siberian mainland, is about 250 miles to the north. The Bering Sea refuge is made up of St. Matthew, Hall, and Pinnacle Islands and offshore rocks. St. Matthew, the largest island, was discovered and named by Sind in 1766 and was visited 12 years later by Capt. James Cook. It is about 30 miles long, from less than 2 to about 6 miles wide, and has an area of approximately 125 square miles. Several mountains exceed 1,000 feet in elevation; the highest mountain, 1,505 feet in elevation, is at Cape Upright at the southeast end of the island. From a distance St. Matthew appears to consist of 10 or 12 separate masses, but actually these are connected by low spits of sand and gravel. The highest points are bare, the lowlands mainly tundra, and the intervening slopes covered with swampy moss and grass. Hall Island, 3 miles from the north end of St. Matthew, is triangular in shape and about 6% square miles in area. Its summit, a 1,665-foot high peak, is the highest point in the refuge. Pinnacle, the third island in the group, lies 9 miles southwest of Sugarloaf Mountain on St. Matthew and is joined to the larger island by a submerged ridge about 300 yards wide between the 10-fathom curves. Pinnacle Island is about 1-1/2 miles long, less than one half mile across at its widest point, and reaches a height of 1,223 feet. The islands are surrounded by pack ice for much of the year and are fog shrouded during most of the short navigation. Although there are no harbors, the U.S. Coast and Geodetic Survey describes several places where ships can anchor but states that landing is difficult when there is any swell because the beach is steep and stony.
The geology of St. Matthew and the adjacent islands is not known in detail. Dall, who visited the islands in 1880, stated: "St. Matthew and its adjacent islets are composed of porphyritic, granitic, and volcanic rocks." Dawson visited the islands for 3 days in 1891 and landed on St. Matthew and Hall Islands. He described several occurrences of pyroclastic rocks of "porphyrite," some of which exhibited columnar jointing. He also published a diagrammatic section of the gently north-dipping rocks on Hall Island. Dawson saw only weathered rocks of volcanic origin but nothing that could be related to recent activity; from this he concluded that the rocks were older than the volcanic rocks on some of the other islands in the Bering Sea. In 1916 Hanna visited St. Matthew and reported that many petrified trees were exposed in a cliff about 2 miles south of Glory of Russia Cape. Dutro and Payne showed St. Matthew and Hall Islands as being made up of Quaternary and Tertiary volcanic rocks. The area covered by the refuge is part of the Bering-Chukchi platform, much of which was exposed at various times during the Cenozoic era as the Bering Sea land bridge. At such times the present islands rose as an isolated range of hills above a relatively featureless plain.
There are no deposits of minerals subject to leasing under the mineral leasing laws in the refuge. Although the lack of detailed knowledge of the geology of St. Matthew and the adjacent islands makes it impossible to state positively that there are no deposits of minerals subject to location, their presence is highly unlikely. None have been found on other geologically similar, better explored islands in the Bering Sea. The isolation of the islands precludes other than local uses of the volcanic bedrock or beach sands and gravels as construction materials.