Zinc is a bluish-white metal (zinc produces a white-green light in a flame test), showing a high lustre when freshly fractured. From Greek and Roman times onwards brass was made by cementing zinc ore to copper. From the 13th century in India a process was known for preparing zinc metal by heating zinc ores with carbon and condensing the resulting zinc vapours. Metallic zinc was imported into Europe from the East in the 16th and 17th centuries. Commercial production in Europe dates from the 18th century. The use of the name zinc by Europeans originates in this period. thus Paracelsus (1493-1541) states (Liber Mineralium):
"Moreover there is another metal generally unknown called Zinken. It is of peculiar nature and origin; many other metals adulterate it. It can be melted; for it is generated from three fluid principles; it is not malleable. Its colour is different from other metals and does not resemble them in growth."
- "Indirect" or "French process" zinc oxide made from the metal.
- "Direct" or "American process," which is zinc oxide made from the ore and, hence, traditionally somewhat less pure.