36 The N.Z. Journal of Science and Technology. [Jan. 
'Marble.- —Has all the uses of limestone, and in addition is used largely as 
an ornamental stone. 
Marl. —Used as a soil-dressing (mainly on account of its carbonate-of-lime 
content). 
Mercury-ore.- —See Cinnabar. 
Mica.—- Extensively used in dynamos, motors, and other electrical appli¬ 
ances as an insulator; for diaphragms of phonographs; for stove 
and furnace windows ; as a heat-insulator; and in manufacture of 
“ micanite,” roofing, wall and other papers, rubber (adulterant), and 
artificial stone. Used also in the preparation of lubricating-compounds 
and as an absorbent. 
Molybdenite. —Yields molybdenum and molybdenum compounds. Used for 
molybdenum steel, in manufacture of cordite (as a preservative), and in 
porcelain-manufacture (as colouring-material). 
Nitrogen. —The nitrogen of the air may be “ fixed ” in various ways (e.g., 
in the manufacture of calcium amide or cyanamide), and so utilized 
for manufacture of nitric acid, nitrates, &c. 
Ochre. —Used in the manufacture of paints of many colours and shades, 
and of clay goods. See also Iron-ochre. 
Oil-shale. —The source of many kinds of oil. Some so-called oil-shales 
approach coal or lignite in composition, and may be used direct as fuels. 
Oxygen. —Nearly pure oxygen may be obtained from the air by many 
processes, and has numerous uses. 
Peat.- —-Used as fuel, as source of gas and oil, as bedding for animals, as 
antiseptic. The peat of many swamps in Auckland contains much 
kauri-resin, and yields valuable oils. Some peats have value as a source 
of nitrogen, which may be produced from them in the form of ammonia 
or other nitrogen compound. 
Phosphate Rock. —-Used as fertilizer, and in porcelain-manufacture. 
Potash Feldspar. —See Feldspar. 
Pounamu (Nephrite, or Greenstone).—-Used for ornamental purposes. 
Pumice. —Used as a heat-insulator, for sound and fire proofing, for paints 
(as a stock), scouring-soaps, metal-polishes, and in concrete. Lump 
pumice is used for wood-polishing, scouring metal surfaces, cleaning 
lithographic stones, &c. 
Pyrite .—Used as a source of sulphur. The residue if thoroughly roasted 
becomes an iron-ore, or may be used for making paint, or for purifying 
coal-gas. 
Quartz. —Used in the manufacture of glass, paint (as a stock), pottery, 
firebricks, silica brick, scouring-soaps, metal-polish, sandpaper, polishing- 
powder, artificial stone, concrete, plastering, and roofing. Used as a 
flux by copper and other metal smelters, as a lining for smelting and 
other furnaces, as- lining for tube mills, for filtering, and for acid-towers. 
Used also by chemical-manufacturers and in the making of ferro-silicon 
and heat-resisting or acid-resisting laboratory ware. See also Sand. 
Resin, Coal.—Commercial uses are likely to be discovered for the resin 
plentifully found in many New Zealand brown coals and lignites. 
Resin, Kauri.—See Kauri-gum. 
Roadmaking Materials. —See Gravel, Sand, Granite, Limestone, and other 
rocks. No full enumeration is attempted. 
Salt, Common.—Besides its everyday household uses, common salt or 
sodium chloride is of immense importance in the manufacture of sodium 
and chlorine compounds, such as carbonate of soda, hydrochloric 
acid, &c. 
