...another reason why stones and the landscape should become sacred, and it had nothing to do with astronomy. At some point after 4000 bc, early humans experienced the apparently magical transformation by which solid rock, when treated in a certain way through heat, can produce molten metal, sometimes of a very different colour.
Pottery was the first of five new substances - the culture of fire - which laid the basis for what would later be called civilisation. The other four were metals, glass, terra-cotta and cement. [use] of pyrotechnological substances underline the continuing importance of fire in antiquity, and show how sophisticated early humans became in their understanding, and manipulation, of heat and flame. Ibid, 67

nb: property detection leads to use, i.e. increasing degree of control over the source-tool axis. diversification.

nb: p.68 on bronze production evolution.