Russia's diamond sources are almost all what?

Russia's diamond sources are almost all what?

• A. Primary
• B. Secondary
• C. Alluvial
• D. Tertiary

Answer: (A)

Diamonds come from two broad source types: primary deposits, which are the original diamond-bearing rocks (like kimberlite pipes), and secondary deposits, where diamonds have been eroded from their source and concentrated in river gravels or beaches. In Russia, the bulk of diamond production comes from primary sources—the diamond-bearing rocks themselves—rather than from alluvial (secondary) deposits. The large kimberlite pipe fields in Siberia, especially in Yakutia, are mined for ore containing diamonds. Alluvial deposits do exist, but they contribute far less to Russia’s output. So the best fit is primary, reflecting that Russia’s diamonds are mostly mined from primary rock deposits rather than from placer deposits.

Diamonds come from two broad source types: primary deposits, which are the original diamond-bearing rocks (like kimberlite pipes), and secondary deposits, where diamonds have been eroded from their source and concentrated in river gravels or beaches.

In Russia, the bulk of diamond production comes from primary sources—the diamond-bearing rocks themselves—rather than from alluvial (secondary) deposits. The large kimberlite pipe fields in Siberia, especially in Yakutia, are mined for ore containing diamonds. Alluvial deposits do exist, but they contribute far less to Russia’s output. So the best fit is primary, reflecting that Russia’s diamonds are mostly mined from primary rock deposits rather than from placer deposits.