The central unit of the weight and monetary system was the (OSw and ODan) mark, (ON) mörk.
1 mark = 8 øre (ON aurar, pl. of eyrir) = 24 örtugar (ON ertogar) = 240 pænningar (ON penningar). The number of pænningar per mark varied considerably over time and area.
In the eleventh century the value of 1 mörk in Norway was c. 214 g brent (pure) silver, the value of 1 eyrir c. 1 ounce. In Iceland the value of 1 eyrir was stipulated to be 6 ells of wadmal; 3 1/3 aurar equalled 120 alnar, which was the value of one cow (1 kúgildi), the equivalent of 1 hundrað. Gotlanders also operated with a gold mark, equivalent to 8 silver marker.
A distinction was made between a weighed mark (mörk vegin) and a current or counted mark (mörk töld). Although they probably had the same value initially − containing the same percentage of silver (90−95%) − the value of the counted mark was gradually reduced.
In the twelfth century, 1 weighed mark was equivalent to 2 counted merkr. OSw law (Upplandslagen) made a similar distinction between karlgild (i.e. weighed) and köpgild (i.e. current) mark. A karlgild mark was worth 50% more than a köpgild mark.
In the thirteenth century Norway the ratio between the weighed mark and the current mark was 1:3, during the fourteenth century 1:4, latter even 1:5. The ration 1:3 was also common in ODan law.
Mark, øre, and örtug were units of calculation rather than coins, only pænningar were used as such. Fines were usually stated in terms of merkr, aurar or ertogar.
Refs: Helle 2001, 157; Hertzberg 1895 s.v. mörk; KLNM s.v.v. mark øre; NK 29, 201−12 and passim; NK 30, 129−30, 152 and passim; Peel 2015, 207; Pettersen 2013, 2−5, 76−84; Robberstad 1981, 306−14; Schlyter 1877 s.v. karlgilder; Tamm and Vogt 2016, 309.
