Dinitrogen complexes (n2) of transition metals have attracted considerable attention since the first report of an m(n2) species in 1965. describe the relevance of n, fixing complexes with special reference to the different classes of complex that exist.

it means there are 3 atoms of oxygen

answer is: naturally occurring solid, inorganic compound or element is mineral.

minerals usually have crystalline form, that means than crystal constituents (atoms, molecules or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

for example magnetite is a mineral of iron oxide (fe₂o₃).

calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (caco₃).

dolomite is an   carbonate mineral composed of calcium magnesium carbonate (camg(co₃)₂).