Definition of mackayite in English:
mackayite
noun
Mineralogy
A green, tetragonal, hydrated tellurite of ferric iron, FeTe₂ O₅ (OH), occurring as pyramidal to short prismatic crystals.
Pronunciation
mackayite
/məˈkʌɪʌɪt/ /ˈmakiʌɪt/ Origin
1940s. From the name of John W. Mackay + -ite.