α. 1500s Guilhelmyte, 1500s 1800s– Guilhelmite, 1600s– Guilielmite, 1700s– Guilelmite, 1700s– Guillemite Brit. /ˈɡɪləmʌɪt/, U.S.
/ˈɡɪləˌmaɪt/, 1800s– Guillelmite, 1900s– Guillielmite.
β. 1600s Guilliammit, 1600s 1800s–1900s Guilliamite.