Instrumentum, the "tool" aspect, is composed of Humanus and Ordo. It is most easily distilled from flint, but also found in any shovel or axe. It has many compounds, of which Machina, Telum and Tutamen are perhaps the most easily available. It is used in a variety of craftings, and in the Infusion Enchanting for tool-specific enchantments. In excess, it can be centrifuged for its useful components.
In research, the "Instrumentum Marathon" refers to the large number of Instrumentum points needed to complete the set of "purchasable" wand and staff core topics, required to enable the research for the Primal Staff Core.