They used the repository's database to find specimens made of stuff—especially basalt, chert (of which the most familiar type is flint) and obsidian—that hominids had a penchant for working into tools before the development of bronze and iron.

他们使用该存储库的数据库来查找由以下材料制成的——岩、燧石（中最常见的类型燧石）和黑曜石——原始人在青铜和铁出现之前就喜欢制作工具。