Various uranium minerals have been found, mostly in small amounts, in a number of places in Texas. Some of these minerals, such as uraninite or pitchblende, are heavy and dark colored. Others, including carnotite, tyuyamunite, autunite, and uranophane, are a shade of yellow or green. They are quite soft. Deposits of the light-colored uranium minerals have been mined from two areas of Texas. One of these areas is in Garza County on the Texas High Plains, and the other is in Karnes and Live Oak counties in the Gulf Coastal Plain. One of the light-colored uranium minerals, _carnotite_, is a potassium-uranium vanadate, which has a bright canary-yellow or lemon-yellow color. This mineral is transparent to translucent and has an earthy or a pearly luster. Carnotite usually is found as crusts and as powdery masses. It is quite soft and can be scratched with a fingernail. Carnotite, along with tyuyamunite, autunite, and several other soft, yellowish or greenish uranium minerals, is found in the Texas Gulf Coastal Plain. These minerals occur in the Jackson, Catahoula, and Oakville strata (which are Tertiary in age) in an area extending from Gonzales County to the Rio Grande (in parts of the area indicated by no. 2 and no. 3 on the geologic map, pp. 4-5). The largest deposits in this district have been found in the Karnes County area. The Gulf Coastal Plain uranium minerals occur mostly with sandstones and clays in a sequence of strata that contains volcanic ash. It is believed that small scattered amounts of uranium compounds that were present in the volcanic ash sediments were dissolved by seeping underground water. These waters then moved into the sandstones and clays where they deposited the uranium as carnotite and as other uranium minerals. Another uranium mineral, _uranophane_ (calcium-uranium silicate), also occurs in Texas. Uranophane has a yellow to yellow-orange color and a pearly to greasy luster. When rubbed across a streak plate, it leaves a light yellow to a light yellow-orange streak. It is soft enough to be scratched by a copper penny. Uranophane has been found in extrusive igneous rocks in northwestern Presidio County in west Texas. A dark-colored uranium mineral, _pitchblende_, is a variety of the mineral _uraninite_, uranium dioxide. Pitchblende does not occur with a crystal shape but rather as rounded and irregular-shaped masses. It is brownish black, greenish black, or black. If you rub it across a streak plate, pitchblende leaves a brownish-black streak. This mineral is heavy (it has a specific gravity of 6.5 to 8.5) and hard (a pocket knife will not scratch it, although a steel file will). Pitchblende has a submetallic luster and looks dull, greasy, or like pitch or tar.