Geology of the Provinces of Canterbury and Westland, New Zealand : a report comprising the results of official explorations
In some former chapter mention has been made of the fact, that large beds of quartzose sands exist in our younger formations, the Waipara formation containing the richest deposits. Generally, they are not quite pure, having some slight admixture of clay, iron, and a few other mineral substances. There are, however, several of these layers of a snowy white colour, being an exact counterpart of the sands of the Brown coal formation in Rhenish Prussia; and as the sands of that country are derived from the decomposition of quartzose trachyte, so the sands of our brown coal beds are portions of decomposed quartziferous porphyry. These sands in Germany are of great value for the manufacturing of glass, and are extensively used for that purpose, and it is worthy of notice that some of these sands, when of great purity, such as those of Bardenberg, Herzogenrath, and Nievelstein, are exported in great quantities to Great Britain for that industry—(Zinken, Braunkohle, Vol. I, page 600). In Bohemia, too, many manufactories of glass are supplied from the products of similar beds. The conclusion, therefore, that the manufacture of glass on a large scale will soon be introduced in New Zealand is not too hazardous; at the same time, we may expect that at no distant date, glass sands will be exported in considerable quantities to England and other countries, principally in ships where ballasting is necessary.