- In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.
- Ptolemy (Wikiquote)
Claudius Ptolemaeus (Greek: Κλαύδιος Πτολεμαῖος; c. 100 – c. 170), known in English as Ptolemy, was an ancient Greek geographer, astronomer, and astrologer who probably lived and worked in Alexandria, off the coast of Egypt.