Gerah

A gerah is an ancient Hebrew unit of weight and currency, which, according to the Torah, was equivalent to of a standard "sacred" shekel.
A gerah is known in Aramaic, and usually in Rabbinic literature, as a ma'ah. It was originally a fifth of a denarius or zuz, as seen in the Torah and in Ezekiel, then became a sixth of a dinar/zuz, such as the coinage of Persian-era Yehud, which came in two denominations: approximately 0.58 gram for the ma'ah and approximately.29 gram for the half ma'ah..58 × 6 = 3.48 grams, which is about the weight of a zuz/denarius based on a 14 gram shekel.
The Mishnah and Jerusalem Talmud in Shekalim discuss whether the kalbon which was sometimes required to be added to the half shekel annually levied for the Temple, was a "ma'ah" or a "chatzi ma'ah".