природное достояние(A good which is not scarce, so that its availability is not an effective constraint on economic activity. A good is not a free good merely because its market price is zero: it may in fact be scarce, but be underpriced by the market because of a lack of enforceable property rights over it. A really free good has a shadow price of zero. A good may be free under some but not all circumstances; ‘free as air' is a proverbial expression, but in mines and other confined spaces air has to be provided at great expense. Oxford Economics Alexander Demidov)