Petroleum is also known as Black Gold -  because when crude oil is extracted from the land it is black in color. People call it gold because of its oils and value . It is very difficult to find. So it is called Black Gold.

Understanding the Term "Black Gold"
Petroleum, often referred to as "black gold," is a valuable natural resource that plays a crucial role in the global economy. This term reflects both its economic significance and its color.

1. Economic Importance
- High Demand: Petroleum is a primary energy source for various industries, including transportation, manufacturing, and power generation.
- Global Trade: It is one of the most traded commodities worldwide, impacting the economies of oil-rich nations and influencing global market prices.
- Job Creation: The petroleum industry generates millions of jobs, from extraction to refining and distribution.

2. Physical Characteristics
- Color: The dark color of crude oil is a distinctive feature that contributes to the term "black gold." It is typically black or dark brown when extracted.
- Valuable Resource: Like gold, petroleum holds significant value due to its rarity and the extensive processes required for extraction and refinement.

3. Historical Context
- Historical Value: The term "black gold" originated in the early 20th century when oil began to be recognized as a vital economic factor, akin to gold in terms of wealth generation.
- Impact on Society: The discovery and commercialization of petroleum have transformed societies, leading to advancements in technology, transportation, and overall quality of life.
In conclusion, referring to petroleum as "black gold" accurately captures its immense value and significance in the modern world, both economically and in terms of its physical properties.