Platinum has only been found in a few cases in the matrix in situ. In the Ural Mountains it occurs as grains in peridotite, serpentine, and olivine-gabbro. The bed-rock of the
Vyzaj and Kaiva Rivers, on the western flanks of the Urals, consists of olivine-gabbro containing disseminated grains of platinum, but not apparently in payable quantities. An olivine rock was discovered in 1893 at Goroblago-datsk, on the western side of the Urals, containing chromite and platinum, the latter at the rate of 14 dwt. 9 gr. to the ton of rock.
Since the discovery of platinum in the nickel-copper sulphide ore at Sudbury, in Canada, careful analysis has disclosed the presence of the metal in minute quantity in many sulphide ores throughout the world. But in this and all cases where platinum occurs in sulphide-beds or in veins, its occurrence is probably not the result of direct magmatic segregation.