Database fields, all categories

Site identification
	`id`	Unique identifying number corresponding to label on map published as Open-File Report 2006-1375. Also used in notes field as an identifier for other operations when capacities are combined.
Geographic location
	`country`	The country in which the mine or processing plant is located
	`dms_lat`	Angular distance measured on a meridian north or south from the equator, expressed in degrees-minutes-seconds
	`dms_lon`	Angular distance between the plane of a meridian east or west from the plane of the meridian of Greenwich, expressed in degrees-minutes-seconds.
	`latitude`	Angular distance measured on a meridian north or south from the equator, expressed in decimal degrees.
	`longitude`	Angular distance between the plane of a meridian east or west from the plane of the meridian of Greenwich, expressed in decimal degrees.
Site characteristics
	`year`	The year for which the plant capacity and activity status is valid
	`op_name`	Name given to a mine or processing plant distinguishing it from others the company owning the facility may have. May be the name of the facility given to it by the company or others in the industry or may be the name of the nearest city or province.
	`op_type`	The type of operation -- may be a mine, an oil or gas field, or one of several kinds of processing plants
	`company`	The principal company operating at the site
	`status`	An indicator of whether an operation was producing during the year listed
	`capacity`	The amount it is possible to produce at the facility
	`units`	The unit of measure for the facility capacity attribute of the site.
	`notes`	Additional information about the record that users should be aware of -- often refers to combined plant capacities
	`method`	The method of mining used by the operation if it is considered to be a mine
Commodities
	`commodity`	The material mined or processed at the site