Other sectors in the province were also hit hard, particularly during the last two decades: coal mining in Cape Breton and northern mainland Nova Scotia has virtually ceased, and a large steel mill in Sydney closed during the 1990s. More recently, the high value of the Canadian dollar relative to the US dollar has hurt the forestry industry, leading to the shutdown of a long-running pulp and paper mill near Liverpool. Mining, especially of gypsum and salt and to a lesser extent silica, peat and barite, is also a significant sector.[19] Since 1991, offshore oil and gas has become an important part of the economy, although production and revenue are now declining.[2] However, agriculture remains an important sector in the province, particularly in the Annapolis Valley.