Various ideas were tossed around, including looking at what real world materials make sense based on the density. Since it is defined in the game, we know the weight of riln, but not very much about the volume of a riln. According to Rias, 400 riln weighs a pound (thanks Rias!). I looked at some common coinage from the USA for a bit of reference:
Code: Select all
Coin mass (g) volume (cm^3) density (g/cm^3)
Penny 2.500 0.433 5.771
Nickel 5.000 0.689 7.257
Dime 2.268 0.340 6.669
Quarter 5.670 0.809 7.009
Half Dollar 11.340 1.582 7.167
Dollar 8.100 1.102 7.349
Penny: 2.617 (aluminum, agate, flint, granite, quartz)
Nickel: 1.646 (magnesium, sugar, soot, bone)
Dime: 3.334 (barium, garnet, ochre, topaz, carbon)
Quarter: 1.402 (calcium, brick, coal, sand)
Half Dollar: 0.717 (sodium, lithium, oak, alum) <- note that this density is less than the density of water (1 g / cm^3), so riln would float at this size
Dollar: 1.029 (sodium, camphor, polystyrene, amber)
Obviously, many (or most) of the materials above wouldn't be a good fit for currency, but some might.