Which statement best describes the difference between primary and secondary deposits?

Which statement best describes the difference between primary and secondary deposits?

• A. They are always in the same location
• B. They are the same thing
• C. Secondary are source rocks; primary are transported
• D. Primary are source rocks; secondary are transported away from the source

Answer: (D)

Primary versus secondary deposits hinge on where diamonds are found relative to their source rock. Primary deposits are where diamonds still occur in their original host rock, like kimberlite, meaning the diamonds haven’t been separated from their source. Secondary deposits, on the other hand, are formed when diamonds are weathered out or eroded from that source rock and then transported by water, ice, or gravity to new settings, where they concentrate in alluvial or placer deposits. So the statement that primary deposits are the source rocks and secondary deposits are transported away from the source best captures the distinction. The idea that they are always in the same location, that they are the same thing, or that secondary are the source rocks would misinterpret the relationship between diamonds and their host rocks.

Primary versus secondary deposits hinge on where diamonds are found relative to their source rock. Primary deposits are where diamonds still occur in their original host rock, like kimberlite, meaning the diamonds haven’t been separated from their source. Secondary deposits, on the other hand, are formed when diamonds are weathered out or eroded from that source rock and then transported by water, ice, or gravity to new settings, where they concentrate in alluvial or placer deposits.

So the statement that primary deposits are the source rocks and secondary deposits are transported away from the source best captures the distinction. The idea that they are always in the same location, that they are the same thing, or that secondary are the source rocks would misinterpret the relationship between diamonds and their host rocks.