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C—lo

of good quality, would afford good sands comparatively free from iron; but with few exceptions the coastal sands recently accumulated may be disregarded. The locality where such sands are of chief and very great importance is the long spit of sand connecting the insular hills of North Cape with the mainland of the northern district of Auckland north of Mongonui and Ahipara. Over this district the quantity of material is enormous, and the highest quality of sand appears in great abundance on the coast lying south of the entrance to Parengarenga Harbour. These sands are pure white, glass clear, and form the spit of land between the ocean and the southern arm of Parengarenga Harbour. They extend south along the shore of Great Exhibition Bay, and from this part of the district alone all the glass-making factories of the world might draw their supplies. The material is clear, glassy quartz, without colouration or stain, except from organic impurities, the peaty soil inland often staining brown the upper part of the sands. This, however, does not affect the sands of the South Spit and the coast of Great Exhibition Bay, whence unlimited supplies can be obtained. Vast accumulations of such sands, but somewhat stained, are to be met with on the shores of Doubtless Bay. These sands are derived from the igneous rocks (quartz diorites) of the district, which are abundant north of a line between Hokianga and the Bay of Islands. These sands were first brought under the notice of the public by the late Captain Fairchild, and were more especially examined by me in 1892. In the South Island, Cape Farewell Spit contains ample material of good quality for glassmaking, but this is less pure and clear, and consequently not so well suited for glass of kinds requiring sand of great purity. Of the sands that lie inland from the coast-line, the principal and perhaps the only important deposits are confined to the Cretaceous system and the coal-bearing formation of New Zealand. The Post-Jurassic denudation of the schistose area of central and eastern Otago resulted in the production of vast deposits of quartz-sands, which are now found at the base of the coalmeasures. Some of these deposits form gravel of moderate size, in which pieces of schist are to be met with. At other places the material is nearly all quartz, and much finer in grain, yet too coarse to constitute glass-sands. Often the material is simply crushed into an angular grit, the individual grains not seldom containing a bluish streak ; but almost everywhere in the localities where the above are found there are beds of pure quartz-sand sufficiently fine in grain and sufficiently pure for the purposes of glass-making. Abundance of such material extends throughout eastern and central Otago and Southland, and occurs on the west coast of the Island within Inangahua, Buller, and Collingwood counties. Apparently drifted north from the Otago region, similar sands are met with along the foot of the mountains that bound the plains of Canterbury on the west. The coal formation, as local patches, is found in the eastern mountainous parts of Canterbury, sometimes near to the foot of the main range, and these glass-making sands usually accompany. In the middle and northern parts of Canterbury Provincial District the glass-making sands are probably derived from the destruction of quartz porphyries that form a belt along the eastern margin of the mountain region between the Ashburton and Waimakariri Rivers. These quartz porphyries are of older date than the series of rocks containing the glass-making sands, and therefore the superior quality of the sands in the Ashburton district may have reference to these rocks adjacent to where the sands are found. The farthest north to which these sands reach in the Canterbury District is the vaUey of the Ashley River, within which occurs, at a place called Glentui, a deposit of very fine absolutely pure, perfectly colourless sand. I noted these sands in 1870, and since then have seen nothing of the kind, so fine in grain and pure in colour, in any other part of the South Island. It were to no purpose to point out all the localities at which sands suitable for glass-making can be found. It is enough to state that there is no scarcity of material; but generally this would require to be utilised within the country, as it is improbable that, except for special purposes, it would pay to export. 11th June, 1901. Alex. McKay.

REPORT ON CHROME-DEPOSITS AT THE CROIXELLES, NELSON. By Alexander McKay, F.G.S., Government Geologist. On the 25th June last I visited the deposits of chromic iron situated on the south side of Croixelles Harbour, Nelson, which are being worked by Messrs. Tatton and Jackson, of Nelson. The chrome-bearing rocks form a belt of soft serpentine immediately, or at no great distance, underlying the Maitai limestone, which latter is strongly developed on the southern shore of the harbour, about two miles inside of the south headland. The direction of the ore-belt is westerly, and from the landing-place a small stream leads in that direction, and takes its rise from a saddle, the waters from which flow westerly into Blind Bay. The height of the saddle is 1,200 ft. above the sea, and it is here that the chief workings for chrome-ore are situated. The ore occurs as no regular, continuous lode, but as elliptic or lintel-shaped masses, sometimes nearly contiguous to each other, but sometimes, also, with a considerable space of nonproductive ground between. Ore is reported on the west side of the valley leading to the saddle, but the chief and workable deposits begin just before reaching the saddle, and extend down its western side for some distance. The principal excavation showing—also the most extensive development of ore—is on the saddle itself, where mined and in sight there may have been at the time of my visit (the 25th June) 150 tons of ore. Deposits of ore had been to some extent worked on down the west slope from the saddle, but these were of less consequence than that which showed on the saddle.