Explanation:

The Indus Valley Civilization, also known as the Harappan Civilization, existed from approximately 3300 BCE to 1300 BCE in the region of the Indian subcontinent. It was a highly advanced civilization that thrived along the Indus River and its tributaries in what is now modern-day Pakistan and western India.

Seals in the Indus Valley Civilization:

- Steatite: Steatite, also known as soapstone, was the most commonly used material for making seals in the Indus Valley Civilization. It is a soft stone that is easy to carve and has a smooth texture. Steatite seals were usually square or rectangular in shape and featured intricate engravings of various symbols, animals, and human figures. These seals were used for various purposes, including trade, administrative, and possibly religious or ritualistic activities.

- Copper: Copper was also used for making seals in the Indus Valley Civilization. Copper seals were less common than steatite seals but were still significant. They were usually smaller in size and featured simpler designs compared to the steatite seals. Copper seals were often used for stamping clay tablets or pottery, indicating ownership or authenticity.

- Chert: Chert, a type of fine-grained sedimentary rock, was another material used for making seals in the Indus Valley Civilization. Chert seals were relatively rare and mostly found in the later stages of the civilization. These seals were typically smaller in size and had more intricate designs.

- Steel: Steel, an alloy of iron and carbon, was not used for making seals in the Indus Valley Civilization. Steel was not yet developed during this time period, and the civilization primarily relied on copper, bronze, and stone for their tools, weapons, and other artifacts.

Conclusion:

In summary, while steatite, copper, and chert were all used for making seals in the Indus Valley Civilization, steel was not available during that time and, therefore, was not used for making seals. The use of different materials for seals reflects the advanced artistic and technological capabilities of the civilization.