Alcaster and the Dark Crystal

I should go check up on Alcaster in El Nath soon. Alcaster of El Nath told me in order to seal The Book of Ancient, he'll need a Dark Crystal and a Star Rock. So here I am, looking for them. The Dark Crystal is supposedly only found from evil-minded monsters, and the ores can be refined by Spiruna in Orbis Park. I got Alcaster the Dark Crystal and the Star Rock. He may have been drained and exhausted from sealing up The Book of Ancient, but his heart seems to be at peace.