page_title: Vein (geology)
section_title: Mineralization and veining
hierarchical_section_title: Vein (geology) / Mineralization and veining
caption_attribution_description: English: Roland Gotthard, own photograph 2004, copyright Roland Gotthard, free use with citation.
context_page_description: 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.
  Veins are classically thought of as being the result of growth of crystals on the walls of planar fractures in rocks, with the crystal growth occurring normal to the walls of the cavity, and the crystal protruding into open space. This certainly is the method for the formation of some veins. However, it is rare in geology for significant open space to remain open in large volumes of rock, especially several kilometers below the surface. Thus, there are two main mechanisms considered likely for the formation of veins: open-space filling and crack-seal growth.
context_section_description: Veins are of prime importance to mineral deposits, because they are the source of mineralisation either in or proximal to the veins. Typical examples include gold lodes, as well as skarn mineralisation. Hydrofracture breccias are classic targets for ore exploration as there is plenty of fluid flow and open space to deposit ore minerals.
  Ores related to hydrothermal mineralisation, which are associated with vein material, may be composed of vein material and/or the rock in which the vein is hosted.
caption: Boudinaged quartz vein (with strain fringe) showing sinistral shear sense. Starlight Pit, Fortnum Gold Mine, Western Australia.
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