Enormous production of weapons-grade plutonium and uranium was undertaken by the PAEC that accounted for more focus towards weapon-grade plutonium. Plutonium is a synthetic element with complicated physio-chemical and metallurgical properties; it is not found in nature in appreciable quantities. The program accelerated when India eventually surprising the world with its first nuclear test in 1974; the development of the atomic bombs became impetus. The uranium enrichment program was eventually separated from the PAEC when Abdul Qadeer Khan founded the Engineering Research Laboratories (ERL) and authority transferred from the PAEC to the military. The enrichment of uranium is a difficult and enduring approach to scale to industrial levels to military-grade; only 0.71 percent of natural uranium (Unat) was uranium-235 (U235), and it was estimated that it would take 27,000 years to produce 1 gram (0.035 ounce) of uranium with mass spectrometers, but kilogram (2.2 pound-35 oz) amounts were required.