Correct Option
The correct option is An alloy of zinc and copper.
Explanation
The Chamba region in Himachal Pradesh is renowned for its ancient tradition of metal casting, particularly for temple idols dating back to the 8th-10th centuries. These figures are typically created using the Cire Perdue (lost-wax) casting technique.
Detailed Analysis
- Composition: While metal icons in Indian art history are often generically referred to as "bronzes" (an alloy of copper and tin), the idols from the Chamba and Kashmir regions are metallurgically distinct. They are primarily made of brass, which is an alloy of copper and zinc.
- Cause of Colour: The distinctive bright, golden-yellow colour of Chamba idols is directly caused by the zinc content in the copper alloy.
- Comparison: Standard bronze (copper and tin), such as that used in Chola bronzes, typically has a reddish-brown hue that darkens or develops a green patina over time. The zinc-copper alloy (brass) retains a lighter, gold-like lustre, which is a hallmark of the Kashmiri and Himachal (Chamba) metalworking schools.
Why other options are incorrect:
- High gold content High gold content: While these idols may look golden, they are not made of gold; the appearance is due to the brass alloy.
- The use of brass exclusively The use of brass exclusively: While true that they are brass, An alloy of zinc and copper is the more precise scientific explanation for the colour (the specific alloy mix). Furthermore, "exclusively" is a strong qualifier, whereas the alloy composition is the direct cause.
- Oxidation over centuries Oxidation: Oxidation generally leads to tarnishing or the formation of a patina (often green or black), not a bright yellow colour.
Key Takeaway
Chamba metal idols are distinctive for being made of brass (Copper + Zinc) rather than bronze (Copper + Tin), which gives them their unique golden-yellow lustre.