Similar
to the compounds of oxygen are those with sulphur, usually named
sulphurets, and considered analogous to the oxidized bases. A few of
more electro-negative character, resembling acids, have been
distinguished as sulphides. Some other compounds have been named
haloid 6alts, and consist of certain electro-negative elements,
combined with electro-positive ones, as bases.
Many
of these combinations occur as independent species in the mineral
kingdom, especially those with, oxygen and sulphur. Tims the most
abundant of all minerals, quartz, is an oxide, and corundum is of
similar nature. Many oxides of the heavy metals, as of iron, tin,
copper, and antimony ; and some super-oxides, as of lead and manganese
(pyrolusite), are very common. Compounds with sulphur also abound,
either as sulphides, with the character of acids, like realgar,
orpiment, and stibine; or as sulphurets, resembling bases, like galena,
argentine, and pyrite. Less frequent are haloid salts, with chlorine
and fluorine, as common salt and fluor spar; and still rarer those with
iodine and bromine. On the other hand, metallic alloys, or combinations
of electro-negative with electro-positive metals, are far from
uncommon, especially those with arsenic, tellurium, or antimony.
Combinations
of these binary compounds with eacli other are still more common, the
greater number of minerals being composed of an acid and base. By far
the greater number are oxygen-salts, distinguished by giving to the
acid the termination ate ; thus sulphate of .lead, silicate of
lime, and in like manner numerous carbonates, phosphates, arsoniates,
aluminates. The sulphur-salts (two metals combined with sulphur, and
these again combined with each other) are next in number, and perform a
most important part in the mineral kingdom. The hydrates, or
combinations of an oxide with water, are also common, and much
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