Idea of Bitcoin Icon
There is a circle with the letter B inside of it. The letter B has four tiny rectangles (all equal size), two on top of it and two on the bottom of it. By having these rectangles attached to the letter B, the letter appears to look like the US dollar sign - - $.
This Bitcoin icon is made in Material Design style
developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 6,200 icons, all in the same style and quality.