Butane is a hydrocarbon derived from petroleum or natural gas. It's extracted during the refining process of these resources.

Here's a simplified breakdown:

1. Petroleum or natural gas is extracted from the Earth.

2. Refining process: The raw materials are processed to separate different components, including butane.

3. Butane extraction: The butane is collected and purified.

4. Packaging: The pure butane is bottled and sold for various uses, including filling lighters.

So, the gas in BIC lighters is a product of refining petroleum or natural gas, a process that extracts different hydrocarbons, one of which is butane.