Question:  Is Dillwynia made of a harder material than an Arrowhead?
Sentence (from "Mohs scale of mineral hardness"): The method of comparing hardness by seeing which minerals can visibly scratch others is, however, of great antiquity, having been mentioned by Theophrastus in his treatise "On Stones", c. 300 BC, followed by Pliny the Elder in his "Naturalis Historia", c. 77 AD.
Relevant evidence: No