The pyrite cube is, well, a cube, so it has a side length s such that the area of its base is
s ² = 5.76 cm²
which means
s = √(5.76 cm²) = 2.4 cm
Then its volume is
s ³ = 13.824 cm³
Pyrite is also known as "fool's gold" because it looks a lot like gold. So if gold has a unit price of €785/cm³, then a pyrite cube with volume 13.824 cm³ could be mistaken for a gold cube of the same volume, which would sell for a price of
(€785/cm³) × 13.824 cm³ = €10,851.80