"There are magic metals???"

"There are! Mithril, orichalcum, bloodsteel, uh, adamantium depending on who you ask - it's not quite a metal and it's not quite magic but it's weirdly affiliated with both."

"Tell me mooooooore."

"Sure! Mithril I told you about. Orichalcum is a little stronger, a little heavier, and a lot more expensive. Magically speaking, it's basically condensed sunlight. Bloodsteel is usually created through enormous amounts of murder, but we've currently got a student who has it running through her veins, so there's kind of an ethical bloodsteel renaissance going right now; it's useful for necromancers and blood mages, who do occasionally do things that aren't nefarious. Adamantium is a compound of several different metals in a matrix of ceramic, so I don't know if it counts as metal for your purposes, but it's the most durable material that can be created by humans without using magic."

"It probably counts for some but not all of my purposes. Condensed sunlight?"

"Yeah - burns vampires, purifies some forms of magical energy like sunlight, generates light and heat indefinitely."

"Is it actually made from sunlight?"

"Sunlight is involved in its creation, yeah - not just sunlight, you need a lot of mithril and gold and some other alchemical reagents too. It's very difficult to make reliably."

"So it's less concentrated sunlight and more an alloy that has sunlight as one of its components?"

"Well, debatably - from a materials science standpoint it's closer to reinforced mithril than anything, but mystically speaking, it is sunlight, or a source of sunlight, and none of the other components stay in it. The mystical definition is the one I'm usually working with, but it makes sense you'd want the physical-world version."

"I want all the versions."

"Sensible. The Mystic Arts department has some very expensive marbles of the various materials that I can show you, too, if you can get better data that way."

"--Ooh, yes."

"We'll take a look when we're in Kirby Hall, then. Speaking of which, should we continue the tour, or do you have more advanced magical theory to ask about?"

"Hah, I think I've exhausted my store of what I know enough about to ask."

They put back their trays and Harry leads them in a counterclockwise circle around campus.

Kirby Hall, as it turns out, is their next stop after he shows them Melville Cottage. It has one door, but then Harry makes a gesture with his left hand, and there's two doors side by side.

"Circe set up the door trick," he explains. "She thinks it's important that nobody be able to get into the Mystic Arts section without having either magic or help from someone with magic. I think she just likes showing off."

"Why would that be important?"

"We've got kind of a rivalry with the Psi department, and she thinks they'd get mad if they knew how much better funded we are than them. The trials and tribulations of academia."

"Ohh, dumb academic rivalries, okay, that makes sense."

"Yep. We're mages, but we're still academics first and foremost."

He shows them inside, then opens the door to a supply closet, which turns out to contain piles of obviously magical artifacts. "Alright, where are the marbles - spare quartz, no, athame, no - that should not be in here, let me -" He slips a silver coin with a strange sigil on it into his jacket pocket.

"Ah, here they are," he says after some more searching, and picks up a Ziploc bag containing five one-inch-diameter marbles - one black, one red, one gold, one silver, one dull steel. He opens the bag and pours them into his hand, then offers them to Emily.

"Eeeeeee!" 

She claps her hands together and bounces up on her toes and the marbles rise into the air, slowly orbiting each other. 

"I've never felt anything like it!"

"Huh - I thought you said your power was magnetism? None of those are magnetic."

"It's magnetism but I can do weird stuff with it. Like push off the Earth's magnetic field to fly."

"Huh. The fifth marble is hypersteel, by the way - like adamantium it's not magical per se, it's a dimensionally nested superposition of about fifty pounds of steel. Very strong and tough, also very heavy so it's less generically useful than other materials."

"It feels really cool."