To farm Blackrock Ore properly a player needs to have their mining skills up to 550. This material is the higher level of the two ores in the expansion Warloard of Draenor. Only found in the new zones within the expansion such as Lunarfall, Frostwall, Shadow Valley, Frostfire Ridge, Talador, Spires of Arak and Ashran. However, Nagrand seems to be the most effective area to farm Blackrock Ore, Like most of the other ores, Blackrock Ore are mostly likely found along the exposed earth surfaces such as cliff edges or foot. An alternate method to obtain Blackrock Ore is to combine ten Blackrock Fragment to create a Blackrock Ore. One this route you will find True Iron Ore as well.
See below for maps and routes for where to farm Blackrock Ore in World of Warcraft: Warlords of Draenor.