1/8/2024 0 Comments Meteorite rock types![]() Refractory inclusions contain lighter colored minerals, like feldspar (which is also a major mineral in light-colored terrestrial granites), so they often look like white patches embedded in the gray matrix. ![]() Some of these objects are spherical, like chondrules, but typically they lack any well-defined shape and are thus called amoeboid. The third component of primitive chondrites are refractory inclusions. This primitive chondrite fell just a few months before the Apollo 11 astronauts landed on the Moon, providing a unique opportunity for scientists to test many of the analytical techniques that they had developed to study the lunar samples. Most of the light-gray objects visible in this sawn slab are millimeter-sized chondrules, while the larger white objects are refractory inclusions both are embedded in black matrix material. These metal grains are particularly obvious in some unequilibrated ordinary chondrites.Īllende is a carbonaceous chondrite which fell in Chihuahua, Mexico. However, they may contain small dispersed grains of metal which will appear as shiny specks on a ground or broken surface. Because these minerals have densities similar to those of most minerals in the Earth's crust, primitive chondrites will not feel unusually heavy for their size. Both chondrules and matrix material are dominated by the minerals olivine and pyroxene (or their alteration products). Unequilibrated ordinary chondrites are dominated by chondrules (up to 80 volume percent), while carbonaceous and enstatite chondrites contain far fewer chondrules (up to 30 volume percent) and in some cases consist entirely of matrix material. ![]() Chondrules are immersed in the second component of primitive chondrites, which is a fine-grained, often soft, porous, and gray material, like spongy graphite, known as matrix. On a broken surface, parts of these millimeter-sized globular bodies may stick out and look like tiny half-buried eggs. Perhaps the most prominent of these are chondrules. Three basic structural components may be visible on broken surfaces. These types of meteorites generally have a dark gray or black fusion crust and a lighter gray interior. To illustrate the variations in their properties, brief descriptions of the different types of meteorites are given in this section. However, other meteorites, particularly achondrites, were produced by the same types of igneous processes that occur on Earth and may be very difficult to recognize. Some meteorites, particularly primitive chondrites, are quite unlike any other type of rock found on Earth and can be readily identified. Since meteorites formed through a variety of processes on many different planetary bodies, they can have substantially different physical and chemical properties. The Structure and Composition of Meteorites
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