Wow... that was tricky... or maybe I'm just dense... the crystals you have to life infuse (air, fire, etc.) have to placed in the world on stone/cobble then broken for the Vis crystals. For someone that knows little about Thaumcraft 6, this was not intuitive. Please add a paragraph to "Elemental Crystals #742" explaining this... and I also recommend you bump the yield to 3 for that life infusion. Doing 12 (9heart) life infusions along with the AS and Botania bits is a bit of a steep climb just to open the door to Thaumcraft (2 sales Mundis and the base 6 for the crafting bench), doing 6 to cover those and have room to maneuver from the start feels less daunting.
Additionally, once you place the crystal down, there is a CHANCE over time that they will "grow". if you break them right away you will only get a single Vis shard, they can expand up to 4 crystals if you are lucky (count them on one surface). so placing them and waiting is a good strategy.