The /ʃ/ sound is spelled with <sh>, <ti>, <ci> or <che>. The /ʒ/ sound is spelled with <si>, <su>, <zu> or <ge>.
This is a contrast between two alveolar fricatives, distinguished only by voicing. Even native speakers may have a problem, but the contrast is so rare that it hardly matters.
The mean density value is very low at 0.2%. The list makes 6 semantic distinctions, a loading of 60%.
Aleutian allusion Aleutians allusions Asher azure Confucian confusion Confucians confusions dilution delusion dilutions delusions mesher measure meshers measures ruche rouge
Credit: John Higgins
(With thanks to Petr R�sel of Mainz.)