The officials wrote on the park's Facebook page the rifle was "exposed to sun, wind, snow, and rain" and features "a cracked wood stock, weathered to grey" and the barrel has "rusted" to brown.
The park said researchers are seeking to answer questions including: "Who left the rifle? When and why it was leaned against the tree? And, why was it never retrieved?"
The Facebook page said the park will allow the public to view the rifle before it is sent off to conservators to undergo treatment and preserve it the way it was found. The rifle will return to the park to be displayed as part of the Great Basin National Park 30th Birthday and the National Park Service Centennial celebration.