Lung Muoi is a tungsten-tin mine in Thanh Cong commune, Nguyen Binh district. This mine was located in the east of Phia Oac mountain range, and was exploited by the French since 1910. The name tungsten is derived from the Swedish words "tung sten" meaning "heavy stone”.

It is a hard steel-grey metal that is often brittle and hard to work. Similar to other mineral deposits around the Pia Oac granite massif, the gas-rich hot magma that intruded (c.85-95 million years ago, Cretaceous period) into the terrigenous-volcanics rocks (shale, sandstone, siltstone ect., formed under rifting ocean c. 250-230 million years ago, Triassic period) had resulted in tungsten and other associated minerals.
Tungsten's many alloys have numerous applications, including incandescent light bulb filaments, X-ray tubes (both the filament and target), electrodes in TIG welding, superalloys, and radiation shielding.
Tungsten's hardness and high density give it military applications in penetrating projectiles.
The tungsten ore is disseminated or nested in quartz veins present inside the granite massif.
The mining method of digging into the fault cliff to create a pit appeared long time ago, and was particularly popular in the 1900s.
Adjacent to the mining site are villa houses and stores built by the French to supervise the mine workers. The Co Hon Shrine was built close to the site to pray for passed-away workers.