Is siderite a gemstone, mineral, meteorite, or all of the above?

In every place I’ve looked, siderite has been shown as something different. An ore, a sort of iron oxide, something found in meteors, a jewel. I’m not very experienced in the way rocks and minerals work. What is siderite? If it’s multiple things, how does it transform from one to another?

I apologize if this is a stupid question.