Uranium

fallup@newsletter.paragraph.com (fallup.eth) — Sun, 06 Nov 2022 07:12:45 GMT

Uranium in unoxidized black ores is tetravalent and in most deposits it occurs as uraninite (an oxide of uranium) and coffinite (a uranium silicate). Pitchblende is a massive, noncrystalline variety of uraninite. The multiple oxides brannerite (oxide of uranium, titanium, thorium, rare earths, and other elements) and davidite (oxide of titanium, iron, and uranium) are the main uranium minerals in a few unoxidized ores. Tetravalent uranium substitutes for thorium and other elements in minerals such a monazite, uranothorite, multiple oxides of niobium, and tantalum, and for calcium in carbonate fluorapatite. It also occurs in unidentified organic compounds in many coaly rocks and marine black shales.

Under oxidizing conditions tetravalent uranium changes to hexavalent uranium and forms oxide, vanadate, arsenate, silicate, sulfate, and carbonate compounds, most of which are hydrous and many of which are bright yellow or green. Carnotite (potassium uranium vanadate) and tyuyamunite (calcium uranium vanadate) are the most common and abundant. Other common minerals include uranophane (a hydrous silicate) and metuzeunerite (an arsenate).

Anthropology

fallup@newsletter.paragraph.com (fallup.eth) — Sun, 06 Nov 2022 06:48:22 GMT

anthropology, “the science of humanity,” which studies human beings in aspects ranging from the biology and evolutionary history of Homo sapiens to the features of society and culture that decisively distinguish humans from other animal species. Because of the diverse subject matter it encompasses, anthropology has become, especially since the middle of the 20th century, a collection of more specialized fields. Physical anthropology is the branch that concentrates on the biology and evolution of humanity. It is discussed in greater detail in the article human evolution. The branches that study the social and cultural constructions of human groups are variously recognized as belonging to cultural anthropology (or ethnology), social anthropology, linguistic anthropology, and psychological anthropology (see below). Archaeology (see below), as the method of investigation of prehistoric cultures, has been an integral part of anthropology since it became a self-conscious discipline in the latter half of the 19th century. (For a longer treatment of the history of archaeology, see archaeology.)