Vein deposits are mineral formations that occur when minerals fill cracks or fractures in rocks. These deposits often contain valuable metals like gold, silver, and copper. The minerals precipitate from hydrothermal fluids, which are hot, mineral-rich waters that move through the Earth's crust. These deposits are typically found in mountainous regions and can be mined through various methods, including underground mining. The concentration of minerals in vein deposits can vary, making some veins more economically viable to extract than others. Understanding the geology of these deposits is crucial for successful mining operations.