Vein (geology)
（重定向自Hydrothermal vein）
![A quartz vein, prominent from the surrounding weathered rock](/Images/godic/202501/19/Quartz_vein_cape_jervis3548.jpg")
![Boudinaged quartz vein (with strain fringe) showing sinistral shear sense. Starlight Pit, Fortnum Gold Mine, Western Australia.](/Images/godic/202501/19/Boudin_vein3549.jpg")
![In situ gold-bearing vein (in brown) at the Toi gold mine, Japan.](/Images/godic/202501/19/Gold_bearing_vein_Toi_Kinzan3549.jpg")
![Gold bearing quartz veins, Blue Ribbon Mine, Alaska](/Images/godic/202501/19/Goldveins13549.jpg")
In geology, a vein is a distinct sheetlike body of crystallized minerals within a rock. Veins form when mineral constituents carried by an aqueous solution within the rock mass are deposited through precipitation. The hydraulic flow involved is usually due to hydrothermal circulation.