Science, Tech, Math › Science Efflorescence Definition in Chemistry Chemistry Glossary Definition of Efflorescence Share Flipboard Email Print Calcium sulphate efflorescence in the rhythmites from Itu, Brazil. Eurico Zimbres/Wikimedia Commons/CC SA 2.5 Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated December 06, 2018 Efflorescence is the process of losing water of hydration from a hydrate. The term means "to flower out" in French, describing the migration of a salt from a porous material to produce a coating that resembles a flower. A good example of efflorescence may be seen in the change of appearance of copper sulfate crystals exposed to air. When freshly crystallized, copper(II) sulfate pentahydrate crystals are translucent blue. Exposure to air causes the crystals to lose water of crystallization. Efflorescence leaves a crusty white layer of anhydrous copper(II) sulfate. Sources Smith, G.K. (2016). "Calcite straw stalactites growing from concrete structures". Cave and Karst Science 43(1), 4-10.Smith, G K., (2015). "Calcite Straw Stalactites Growing From Concrete Structures". Proceedings of the 30th 'Australian Speleological Federation' Conference, Exmouth, Western Australia, edited by Moulds, T. pp 93 -108.