Antimony is a chemical element and one of its uses is to create the blue colour in fireworks.
The mineral calcite is often associated with stibnite and can clearly be seen on many of the needle-like crystals. Each crystal sparkles incessantly as it catches the light at almost every angle.
There's an overwhelming temptation to keep wanting to touch the crystals but stibnite should really be handled as little as possible. It's exceptionally fragile and grades just 2 on Mohs scale of mineral hardness. To put that into perspective it's only very slightly harder than the clay mineral talc used to create talcum powder.