Silver has many uses. Like gold, it is a beautiful metal that long has been used for coins and ornaments. A large amount of silver goes to make articles such as spoons, forks, platters, and trays. The photographic industry uses silver—much of the film for cameras is coated with a silver halide. Doctors and dentists use silver, too. The mixture that a dentist uses to fill teeth contains silver along with several other metals. Doctors sometimes use silver wire to fasten broken bones, and silver compounds and solutions, such as silver nitrate, are used in some kinds of medical treatment. Perhaps more people have heard of legendary, lost silver mines of Texas than of the actual and important silver deposits found in the Trans-Pecos country of west Texas. Some of the west Texas silver minerals include _argentite_, _cerargyrite_, and _native silver_. Although the argentite and native silver commonly found there are mixed with galena, a lead mineral, or with chalcocite, a copper mineral, they also occur separately. The element silver is found alone as _native silver_. When pure, it is rather easy to recognize. It is metallic and has a silver-white color that may tarnish to gray, black, or yellowish brown. Native silver is heavy (it has a specific gravity of 10.5) and soft (a pocket knife scratches it easily). When you rub it across a streak plate, native silver, unless it is tarnished, leaves a shiny, silver-white streak. This metal is so ductile that it can be drawn into a wire. It is also malleable and flattens when hit with a hammer. Silver occurs as crystals, which are poorly shaped cubes and octahedrons, or as irregular masses. It may have a net-like appearance (called _reticulate_), or it may be shaped like little needles (described then as _acicular_). It occurs in wires (then called _filiform_) or as scales or plates. [Illustration: Prospector.] Two of the Texas silver minerals, _argentite_ and _cerargyrite_, do not resemble silver at all. _Argentite_, a silver sulfide, is also called _silver glance_. It is a dark, lead-gray mineral with a metallic luster that weathers to a dull black. When you rub it across a streak plate, argentite gives a shiny, blackish to lead-gray streak. This mineral is soft enough to leave a mark on paper. It has a specific gravity of 7.3, and it is sectile enough to be cut smoothly (like soap) with a knife. In some places argentite is found as irregular masses or as a coating on rocks and other minerals. Another silver mineral, _cerargyrite_ (or _horn silver_) is a silver chloride. This mineral has a nonmetallic luster and is transparent to translucent. It resembles pearl-gray, white, greenish, or colorless wax. When exposed to the light it turns violet brown or black. Cerargyrite is soft—you can scratch it with a fingernail. Like argentite, it is sectile. This mineral has a specific gravity of 5.5, and it commonly occurs as irregular masses and as crusts.