Neon is a rare gas in the Earth's atmosphere, but is found in the form of gas molecules with a single Neon atom. Neon would need to be refined from the air or produced in the laboratory.
Cerium is found as a compound of many other rare earth metals, so it is processed using several acids and techniques that rely on the properties of the other metals and their compounds to remove them.
Chemical herbicides are weed killers made in the laboratory, not from nature.
The hydrogen peroxide is not found in the nature, it is man made.
Natural diamonds are formed by Mother Nature: man-made diamonds are manufactured in a laboratory.
Petro is a refined substance made from crude oil.
it is fount in nature.
About 28 elements were discovered in the laboratory. But after the man made preparation some elements were discovered also in nature in very extremely traces: Pm, Tc, Pu, Np, Am, Cm, Bk.
Platinum is found in the nature in elemental form.
antimony is found naturally
Elements found in nature are referred to natural elements, as opposed to synthetic, which are man made.
helium
Trinitrotoluene is man made.