Help please indentifying ancient coins: 6 of 8

[Jack-the-Lad]

Hello,

As a complete newbie, I would really appreciate any help identifying this coin.  There are 8 in total, separate emails.

COIN # 6

This one is (in millimeters):

Longest axis:      34.9

90° away:           33.8

Thickness:          3.35

My scales aren’t accurate enough to weigh it with any degree of certainty, but I’d guess ~21 grams but this could be way wrong.

The metal appears to be copper perhaps, given the green corrosion.

[JKK]

That looks like an early Imperial sestertius. Does the metal look brassy? They were made of orichalcum, a brass alloy. Unfortunately there is not enough legend to learn much, except that someone was a consul (which emperors typically had been multiple times; if one can read a numeral after COS, that's normally a starting point). I can't make anything of the reverse, not even the SC.