Definition of portlandite in English:

portlandite

Pronunciation /ˈpɔːtləndʌɪt/

noun

Mineralogy
  • A mineral of the hexagonal crystal system that is a form of calcium hydroxide that occurs naturally as minute colourless plates and is a common product of the hydration of Portland cement.

Origin

1930s. From the name of Portland + -ite, after Portland cement.