ECONOMICAL MATERIALS. 
421 
and of a quality suitable for the best drawing pencils, but not in sufficient abundance to give 
it a commercial value. The demand for this article is now so great, that careful search for it 
is warranted. 
Precious stones. The zircon of Rossie is in sufficient perfection for cutting and setting in 
all ornamental work, as rings, bracelets, broaches, etc. The black quartz, in dodecahedral 
crystals, is sometimes handsome, and may possibly be found in the iron mines in sufficient 
perfection to admit of being employed in ornamental work. The finest materials for these 
purposes, however, is the labradorite, which may be obtained in large pieces. One or two 
fine specimens of calcedony have been found in the trap dykes, which were truly gems. 
The preceding list of substances is inserted for the purpose of pointing out several mine¬ 
rals, which would be accounted abroad as worthy of special attention. The list of natural 
productions which are used in the arts is daily enlarging, and soon very few of them will be 
passed by with indifference. 
The iron ores do not appear in the above list, as they have been described so fully, that all 
the facts in relation to them have been stated. 
