What is a deposit called where gems are found in the rock that carried them to Earth’s surface?

The term "primary deposit" refers to the original source or location where gemstones are found in the rock that brought them to the Earth's surface. These deposits are often associated with the geological processes that formed the host rock, meaning the gems are found directly in the matrix or the rock itself rather than having been transported and altered by natural forces.

In primary deposits, gemstones are typically mined from their host rock and have not undergone significant weathering or transportation. This contrasts with alluvial deposits, which are formed when gems are eroded from their primary source and transported by water to other locations, often resulting in a different geological context. Similarly, eluvial deposits occur when materials are washed away but remain close to their source, and secondary deposits could refer to those transported or altered after their initial formation. Understanding how gemstones are located helps in identifying mining methods and estimating the quality and character of the gems.