Sadly, there is no knowledge to be mined. Unless the legendary Quaesitum Mines of Langoria turn out to be more than legendary, you're stuck with pure physical substances. Earth is very sorry.
Meanwhile, you do MINE ALL THE THINGS! You get very into it and find a substantial haul. Tara comments on your good luck.
(+6 Redstone, +2 Copper, +2 Tin)
When you finally sit down to take a break, you finally take that there Mechanics Textbook and figure out what the hell this is all about. Tara helpfully directs you to the section on electrical mechanics. Ah, yes. Those crystals are going to come in handy. Apparently, some of them generate electricity when heated, including by friction of movement. According to the book, these are called Langston crystals. And no, Tara doesn't have a better name either. She does have quite a few of these crystals, though.
(Basically a stand-in for a generator assembly. So many electromagnets!
Anywho, it may be worthwhile to note that crystals come in Large size and split into 10 Mediums,which each split into 10 Small which each split into 10 Tiny which can each be ground into 10 Powdered units. Most crystals still work when split apart or even powdered.)
EDIT: When asked about your idea of getting an engraving, the Mechanic just shrugs. "He'll be glad to take your money."
Inventory:
1 Steel Pickaxe
1 Pretty Sweet Helmet with Headlamp
1 set of Clothes
1 Above Average Iron Sword with Copper Handle
26 units of Redstone
9 Iron
4 Copper
5 Tin
1 Wrench!
7 Large Crystals
1 Focusing Crystal (Enhances light!)
1 Conductor Crystal (Conducts electricity!)
Mechanic's Textbook
Home: Mineshaft!
1 Decent Bed
1 Oven
Skills: Proficient Miner
Adequate Swordselemental
Dabbling Mechanic
Attune, Level 1: Learn skills with metal weapons and tools much faster.