Swissmiss asks, hey, what’s that in your drink?
Not recommended for those suffering from pica or ice-chewers who are absent-minded.
However, this is almost all marketing and little (ahem) solid physics.
Nordic Rock is mined from ancient Swedish pollution-free base rock. It is the purest way of cooling your drink – literally ‘on the rocks’. Stone does not melt, which means no unclean water in your glass. They are also reusable making them very eco-friendly. To use, simply place the stone ice cubes in the freezer for approximately one hour before use. For a normal glass, two or three Nordic Rocks will be fine. They give off their cold gradually and equally.
Not diluting the drink is a valid claim (technically chemistry, though). Cleanly or not, though — don’t you use clean water in ice cubes? Ewww.
“Eco-friendly?” How much water does it take to clean these, as compared to the amount of water in an ice cube?
“They give off their cold gradually and equally.” Reasonable claim, once you get past “cold” being a substance. But the advantage of water is that, because of the latent heat of fusion (334 J/g), your drink will stay at 0 ºC until the ice melts, while the drink with the stone cubes will warm up continually. And what’s the heat capacity? I’m not sure exactly what these are (don’t recall “base rock” being a designation), but I’ll assume they are similar to granite, whose heat capacity is about 2 J/cm3 K (helped by its higher density), similar to ice, while water is 4.18 J/cm3 K, and again there’s that huge amount of energy from the latent heat. Let’s say you have 10 cm3 of these stones at 0 ºC and an identical amount of ice. The stones will absorb just 400 or so J of energy in warming to 20ºC, while the ice will absorb 3000 J just in melting, and then 750 more in warming up. Thermodynamically, ice wins.
If you don’t like the dilution of ice cubes, you’re better off using water frozen inside of another container, as in the trick I offered a little while back.
