Question

Nickel ores are NOT associated with

• A. ultramafic igneous rocks
• B. laterites
• C. sea-floor polymetallic nodules
• D. skarns

Answer 1

The Correct Option is D

Nickel Ore Deposits and Their Geological Associations 

Common Geological Settings for Nickel Ores

Nickel ores are commonly found in specific geological environments, including:

• Ultramafic Igneous Rocks: These rocks, rich in magnesium and iron, often host nickel sulfide deposits.
• Laterites: Formed by intense weathering of ultramafic rocks, leading to nickel-enriched lateritic deposits.
• Sea-Floor Polymetallic Nodules: Contain significant amounts of nickel along with manganese, copper, and cobalt.

Step 1: Identifying the Incorrect Association

• Skarns: A group of metamorphic rocks formed by contact metamorphism of calcareous rocks.
• **Skarns are not a primary source of nickel**, as they are more commonly associated with tungsten, iron, and copper mineralization.

Step 2: Determining the Correct Answer

Since skarns do not typically host nickel ores, the correct answer is:

\[ \mathbf{(D):\ Skarns} \]

Final Answer:

Thus, nickel ores are not typically associated with skarns, making the correct option: (D).