In economies with an unstable currency, barter and other alternate currency arrangements such as dollarization are common, and therefore when the 'official' money becomes scarce (or unusually unreliable), commerce can still continue (e.g., most recently in Zimbabwe). Since in such economies the central government is often unable, even if it were willing, to adequately control the internal economy, there is no pressing need for individuals to acquire official currency except to pay for imported goods. In effect, barter acts as a protective tariff in such economies, encouraging local consumption of local production. It also acts as a spur to mining and exploration, because one easy way to make money in such an economy is to dig it out of the ground.