What is the minumum height for a mechitza? Can part of it be see-through? and what sources can these halachot be derived from?
According to HaRav Moshe Feinstien the best michitza is a balcony. (Igrot Moshe, Orach Chaim, vol1: 39) If that is not possible than a michitza should be as high as the women's shoulders which is 18 tefachim according to Tosfot and 17 and a third according to Rashbam. 60 inches - 5 feet. (Igrot Moshe, ORach Chaim vol 3:23) The mitzvah of a michitza is a Torah requirement in order that there should not be a frivolous atmosphere in the Synagogue. The reason for the michitza is not to prevent men from seeing women but rather to prevent a social frivolous scene. (vol 1:39) However if women come to the Shul dressed immodestly than there is a problem with seeing the women as well. Women who come with out head coverings is not considered immodest according to Rav Moshe and the Aruch Hashulcahn and one may pray next to a woman who uncovers her hair. (vol 3 24). A see-through michitza would be okay if it begins over 5 ft, however each shul is built differently, and any practical halacha concerning a michitza in shul needs to be decided by the Rav of that Shul. If there is no Rav, one should be brought in to decide on the michitza. The main thing is that there should not be any quarrellings concerning the michitza. Source information can be found in Igrot Moshe,Orach Chaim, vol 1:39.