Emeralds are rarely found in placer deposits because they are:

Emeralds are indeed rarely found in placer deposits primarily because they are unable to withstand much abrasion. They are a variety of beryl, which has a relatively lower hardness compared to other gemstones. In placer deposits, gemstones are typically subjected to significant erosion and transportation processes that can wear down softer stones, leading to their fragmentation or loss. Emeralds, being softer, do not endure these processes well, making it unlikely for them to accumulate in riverbeds or sedimentary environments like other, more durable stones might.

Placer deposits are commonly characterized by the presence of harder gemstones that can survive the natural forces involved in weathering and transport. As a result, gemstones that are more resilient, such as sapphires or diamonds, are often found in such settings while emeralds are less frequently encountered. This concept emphasizes the importance of a gem’s durability when considering their occurrence in different geological environments.