Explanation:

Harappan civilization was one of the earliest and largest urban civilizations of the world, which flourished in the Indus Valley from 2600 to 1900 BCE. They were known for their impressive bronze and copper artifacts. On the other hand, Oman was an important center for the production and trade of copper in the ancient world.

Chemical analysis of Omani copper and Harappan artifacts has shown that both have traces of nickel. Some of the key points explaining this are:

- In ancient times, copper was often alloyed with other metals to improve its properties. Nickel was one of the most commonly used metals for this purpose.
- Omani copper was highly prized in the ancient world for its purity and malleability. It was widely used for making weapons, tools, and decorative objects.
- Harappan artisans were known for their skill in casting and shaping bronze and copper objects. They produced a wide range of objects, including figurines, vessels, and tools.
- The discovery of nickel in both Omani copper and Harappan artifacts suggests that these two civilizations had contact and trade relations with each other.
- The presence of nickel in the alloy also indicates that these ancient artisans had a sophisticated knowledge of metallurgy and were able to create alloys with specific properties for different applications.

In conclusion, the discovery of nickel in Omani copper and Harappan artifacts provides insights into the ancient world's technological advancements and trade relations.