Mandaic was an
ancient script (in very spare usage today) based off of
Syriac. It was meant to write Late
Aramaic in
Iran. It was an
abjad, and unlike a similar
Koine writing system used to this day to write
Aramaic, it made no use of vowel diacritics. Instead, the abjad extended the use of mater lectionis.
The concept of mater lectionis (which means 'mother of reading') is somewhat difficult, but absolutely essential to abjad languages without an exact way of expressing vowels. Imagine if in English we did not have characters for 'a', 'e', 'i', 'o', 'u', or 'y'? Well, we could make up characters for them, but in a highly historic or conservative society this would be difficult. So how about taking some letters that aren't used very often and substituting them? For example, 'x'. It's really not used in too many words, so most of them time it could represent something else. Same for 'q' and 'z'. This method is employed in modern abjads like Arabic and Hebrew, so despite how cumbersome it sounds, the system works. Unfortunately, Aramaic had more important vowels to deal with than either of those Semitic languages, and the substituted consonants were confusingly and inconsistantly used. Sometimes they could stand for one vowel, then another, then finally for themselves.
The appearence of Mandaic is angular and similar to Arabic or Aramaic. It is written cursively, with certain letters breaking off the flow mid-word.
Information sourced from Daniels, Peter T. Bright, William. The World's Writing Systems. Oxford: Oxford University Press, 1996.