National stockpiles also include known resources .. material that has been sufficiently sampled and measured to have a well enough known to near certainty layo

National stockpiles also include known resources .. material that has been sufficiently sampled and measured to have a well enough known to near certainty layout of various densities of the ore of interest .. AND .. a sound plan for extraction that is "economically feasible" with known and costable technology. Resolution Copper counts to some as part of the USofA national stockpile of copper, albeit as yet unmined, contested for environmental and native title reasons, and with mineral leases held by a transnational company. https://en.wikipedia.org/wiki/Resolution_Copper https://en.wikipedia.org/wiki/Resolution_Copper Rio Tinto has reported an inferred resource of 1.624 billion tonnes containing 1.47 percent copper and 0.037 percent molybdenum at depths exceeding 1,300 metres (0.81 mi). The proposed mine is one of the largest copper resources in North America. Following the passage of the 2015 National Defense Authorization Act, many Native American and conservation groups oppose the copper mine because it will destroy the area above Oak Flat and around the deposit.