RUSSIA/Three Five Kopeck pieces of Catherine II CE 1762-1796

all large coppers 40-42mm in diameter and each exceeds 50 g in weight. and about 4-5mm in thickness.
each was minted at the Yekaterinberg mint designated by the mm of EM on the obs. and has the accompanying denomination inscribed as ПЯТЬ КОПѢЕКЬ under the imperial eagle. 
The initials of Catherine appear in the center of a wreath with the date of the coin to the right and left.

1769 42mm C 59.3

1777 42 mm C 59.3

1780 40mm C 59.3

according to the dealer who sold these pieces, they came from a hoard found outside St. Petersburg but no further details were provided as to the date of the find or that it consisted of anything other than 5k pieces.