This type is listed by KM under Mainz and by Schön DM and Gräßler under Erfurt. Gräßler lists many variants of this type: Gräßler# 192-A196 (1768) and Gräßler# 208-224.3 (1769). Only KM lists the date 1770. Coins with the date 1770 probably have the KM number 374. If you have a coin with the KM number 364 from 1770, please include an image of the minting sequence.
Erfurt belonged to the Archdiocese of Mainz, and the Mainz bishops had coins minted in Erfurt. These are actually Mainz coins with the Erfurt mint. Of course, these were also used in Erfurt and are often referred to as Erfurt coins because of the coat of arms (Erfurt also has the Mainz wheel).