Hematite is the mineral form of iron oxide. It is the oldest known iron oxide mineral that has ever formed on earth, and is widespread in rocks and soils. On its own it's not the prettiest stone but I love the mix of heart shapes with other gemstones.
In Ancient Rome, Hematite was a popular stone for decorative purposes. Jewellery, weapons, and even armour decorated with Hematite were traded widely.
It is said to be a good stone for organising one’s thoughts and developing logical thinking skills - useful for subjects such as mathematics, argumentation and debate, or problem-solving.