Zechsteen or Zechstein: How To spell?

The word Zechsteen is misspelled against Zechstein, a noun meaning "The upper division of the Permian (Dyas) of Europe. The prevailing rock is a magnesian limestone."

Word contains consecutive vowels 'EI' in between alphabets zechst & n is misspelled as 'EE'
Wrong Spelling:  zechst-ee-n 
Correct Spelling:  zechst-ei-n 
Explore spell check of Zechstein to spell without errors.