Pine Mountain is a rhyolitic mountain east of Bend and south of U.S. Route 20 (US 20) in eastern Deschutes County, Oregon, United States. It is the site of an astronomical observatory called the Pine Mountain Observatory. The mountain is a part of the Deschutes Formation (which is related to Cascade volcanism) and is the southeasternmost exposure of the formation and is of similar age to Cline Buttes.