Redstone is for crafting and brewing. Redstone can be obtained by mining redstone ore with an iron pickaxe or better, by trading with priest villagers, or by killing witches. Redstone can be placed on the ground to make redstone wire, can be crafted into numerous redstone components and devices, or used in brewing potions.
Redstone
Redstone can be found in small viens, and each ore contains 4 or 5 dusts. They are pretty common deep under ground and are usally useless.
Uses
Artifice
Bibliocraft
Falling Meteors
Harken Scythe
LegendGear
Project Zulu
Secret Rooms Mod
Tinkers' Construct
Twilight Forest
Xeno's Reliquary