Neo-formed minerals

The mineralogy of ferricrete alteration profiles can be complex and varied because of the incorporation of mechanically derived materials and the retained importance of host rock composition after the formation of secondary minerals. In general, ferricrete profiles do not display the progression of alteration minerals observed in laterites. Where ferricretes are formed by mechanical accumulation, they can lie disconformably above unaltered bedrock (Bowden, 1987, 1997). In these instances, the ferricrete mineral assemblage will be inherited, in part, from the derived materials, and in part from later cementation processes that involve remobilised iron and alumina deposited as neo-formed oxyhydroxides. In such examples, determining the sequence of mineralogical transformations becomes exceptionally difficult. 

As a continuation of these early observations, bone defects surgically produced in sheep and rabbit models were treated with freeze-dried methylpyrrolidinone chitosan (Muzzarelli et al. 1993b, 1994, Mattioli-Belmonte et al. 1995). Histological examination performed 60 days after surgery showed a considerable presence of neo-formed bone tissue as compared to control. Endosteal, periosteal, and bone marrow osteoblast-like precursors, stimulated by growth factor entrapped in the polysaccharide, generated intramembranous bone formation. Bone osteoid formation was followed by mineralization. Osteoinduction was also observed in rabbit endochondral bones (Borah etal. 1992). 

Gr. neos, new, and didymos, twin) In 1841, Mosander, extracted from cerite a new rose-colored oxide, which he believed contained a new element. He named the element didymium, as it was an inseparable twin brother of lanthanum. In 1885 von Welsbach separated didymium into two new elemental components, neodymia and praseodymia, by repeated fractionation of ammonium didymium nitrate. While the free metal is in misch metal, long known and used as a pyrophoric alloy for light flints, the element was not isolated in relatively pure form until 1925. Neodymium is present in misch metal to the extent of about 18%. It is present in the minerals monazite and bastnasite, which are principal sources of rare-earth metals. 

---