Answer:
The mineral you are referring to is called magnetite. Its chemical formula is Fe3O4.
Step-by-step explanation:
Magnetite is composed of three parts iron (Fe) and four parts oxygen (O). Magnetite is highly magnetic and is one of the most abundant naturally occurring magnetic minerals found in the Earth's crust.
When magnetite possesses magnetic polarity and acts as a natural magnet, it is often referred to as lodestone. Lodestone is a naturally magnetized form of magnetite and has been used for various purposes throughout history, such as navigation and the creation of compasses.