A MINERAL is a naturally occurring, solid substance.
A ROCK is a combination of one or more minerals.
- Rocks created by volcanic activity are known as igneous.
- Rocks made from compressed layers of sediment are sedimentary, and rocks formed when changes in temperature or pressure cause one type of rock to change into another are called metamorphic.
- Rock-forming minerals are classified according to the elements they are from.
- Elements are the basic building blocks of all matter. Just eight elements (oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium) make up nearly 99 percent of Earth’s crust. These and other elements combine to form the minerals that in turn combine to create rocks.
An ore is a rock containing valuable mineral deposits that are economically profitable to extract.
- Bauxite ore is the main source of aluminum. Aluminum conducts electricity well, is lightweight, and resists corrosion. Aluminum is the second most widely used metal after iron. Aluminum is the most abundant metal on Earth. Aluminum is almost never found in its native state. Instead, it is found combined with other minerals in various ores. Other important metal ores include sphalerite (zinc), nickeline (nickel), cassiterite (tin), galena (lead), and cinnabar (mercury).
- Bauxite was named after Les Beaux-de Provence in France where it was first discovered in 1821.
- Aluminum has many uses, including making power lines, aircraft, beverage cans, cooking utensils and more. Aluminum compounds (mixtures) are used in the production of glass and ceramics, and in the manufacture of jet fuel, paints, and antiperspirants.
The source of this water is one of biggest mysteries in understanding, not only the Earth’s evolution, but also that of the Moon, Mars, and even the asteroids, says Terik Daly, a planetary scientist now at Johns Hopkins University, in Baltimore, US.
One concern is that as these bodies formed stepwise from repeated collisions, a great deal of heat was released by each impact. And because they were smaller than the present Earth, these bodies had less gravity, which scientists thought would cause any water that reached them via such collisions to boil off into space.
But we know that the Earth has water, as do asteroids. Even the Moon appears to have water trapped within its mantle.
(Boston) – Researchers from Boston University discovered the remnants of the largest crater in the Sahara, which may have been formed by a meteorite impact tens of millions of years ago. Dr. Farouk El-Baz made the discovery while studying satellite images of the Western Desert of Egypt with his colleague, Dr. Eman Ghoneim, at BU’s Center for Remote Sensing.
The double-ringed crater – which has an outer rim surrounding an inner ring – is approximately 31 kilometers in diameter. Prior to the latest finding, the Sahara’s biggest known crater, in Chad, measured just over 12 kilometers. According to El-Baz, the Center’s director, the crater’s vast area suggests the location may have been hit by a meteorite the entire size of the famous Meteor (Barringer) Crater in Arizona which is 1.2 kilometers wide.
The scientists can’t be sure how long ago the Kamil meteorite crash occurred, but they estimate it was roughly a few thousand years ago ? in other words, relatively recent, in geological terms.
There are only about 175 confirmed Earth impact craters, even though the planet is barraged by space rocks slamming into it relatively often. Yet most craters are worn away easily on the ever-changing surface of Earth.
“This is important because small impacts are rather frequent on Earth ? on the order of one event every 10 to 100 years,” Folco said. “So studying this crater is a good opportunity for scientists to get to a correct assessment of the hazard small impacts pose to the Earth and to devise mitigation strategies.”
Objects about the size of washing machines typically fall into Earth’s atmosphere every month, but most burn up before they can reach the ground. Many of the resulting fireballs are not seen because they occur over remote areas or over the ocean. The Earth is more than two-thirds ocean.