Tertiarum is a term that was used by Pliny the Elder in 1st century AD for a solder made of 1 part tin and 2 parts lead.  He referred to Tin as white lead and the other as black lead.  This solder was very valuable at $70 per kilogram according to the math that was done by H Rachham in his book, Pliny: Natural History Book 34.  He determined, "the price of the alloy was 20 denarii per pound.  With 25 denarii (silver pieces weighing approximately 4 grams or .14 oz each) to 1 gold aureaus of close to 8 grams (0.28 oz), the price of Roman solder works out at $70 per kilogram, assuming that gold has maintained it purchasing power since Pliny's day."