![]() ![]() Like other chondrites, carbonaceous chondrites have experienced various degrees of aqueous alteration, thermal metamorphism, or a combination of the two. The dark appearance has more to do with the greater abundance of fine-grained matrix in them than in most chondrites. Although some carbonaceous chondrites contain up to 2 percent carbon by weight in organic matter, others contain less carbonaceous material than some members of other classes of chondrite. This class of chondrites originally was assumed to be rich in carbonaceous material because of the gray-to-black appearance of many of its members. The name carbonaceous is something of a misnomer. Like all chondrites, carbonaceous chondrites (with the exception of the CI group) are composed principally of chondrules and refractory inclusions set in a fine-grained matrix. Two additional groups, named CH and CB, has also been tentatively identified. Carbonaceous chondrites are subdivided into six well-established groups-CI, CM, CV, CO, CR, and CK-based on their bulk chemistry, petrology, and oxygen isotopic compositions. They comprise about 3 percent of all meteorites collected after being seen to fall to Earth. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!Ĭarbonaceous chondrite, a diverse class of chondrites (one of the two divisions of stony meteorites), important because of the insights they provide into the early history of the solar system.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives. ![]()
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