[Galena], lead sulfide, is a shiny, lead-gray, metallic mineral that has a [specific gravity] of 7.4 to 7.6. It is soft enough to mark paper, and it leaves a grayish-black [streak] on a streak plate. This mineral cleaves perfectly in three directions, and the [cleavage fragments] have square corners—some are [cubes].
[Galena] occurs as cleavable masses, as fine or coarse grains, and as crystals, most of which are [cubes]. Galena commonly is associated with other minerals; for example, some of the west Texas galena either contains some silver (then called argentiferous galena) or occurs with it. Sphalerite, a zinc mineral, is commonly found with galena.
[Galena] is an important mineral because it is the chief source of lead. Compounds of lead, called white lead, red lead, and litharge, are used as paint pigments. Automobile batteries contain lead plates, and tetraethyl lead is added to gasoline to keep the car’s motor from knocking. Some other uses of lead are in bullets, type metal, solder, and cable coverings.
[Galena] has perfect cubic [cleavage]. The three directions of cleavage are at right angles to each other resulting in cubic cleavage fragments.
[Galena] has been found in several areas of Texas and has been mined in central and west Texas. None, however, has been produced in [recent] years. Most of the galena mined in west Texas was obtained from silver mines, where the galena was a by-product. Some of the west Texas galena deposits are at Altuda Mountain east of Alpine in Brewster County, in the Eagle Mountains and the Quitman Mountains in Hudspeth County, and in the Chinati Mountains and the Shafter area in Presidio County. Most of the mining has been from the Shafter area (this area is described with [silver minerals] on [p. 90]).
In central Texas, several small [galena] deposits have been found in Blanco, Burnet, and other counties of the [Llano uplift] area. Some galena has been mined at Silver Creek in northwestern Burnet County. Here, galena occurs in cracks and as scattered grains in [Cambrian] limestones and sandstones.
It is probable that much of the [galena] in west Texas and in central Texas was formed when hot [magma] forced out solutions containing lead. These solutions moved up through cracks and other openings in the subsurface rocks and deposited the galena in them.
Small amounts of [galena], which likely had a different origin, have been found in Fisher, Foard, Hardeman, and Young counties. A little occurs also in rocks associated with [salt] in a number of the [Gulf Coastal Plain] salt domes.