Alloy are relatively similar in size, the atom exchange method usually happens, where some of the atoms composing the metallic crystals are substituted with atoms of the other constituent. This is called a "substitutional alloy". Examples of substitutional alloys include bronze and brass, in which some of the copper atoms are substituted with either tin or zinc atoms respectively. In the case of the interstitial mechanism, one atom is usually much smaller than the other and can not successfully substitute for the other type of atom in the crystals of the base metal. Instead, the smaller atoms become trapped in the
Sundown Tin and Copper Mine above the dams, leaching the metallic salts and having a strongly sulphurous smell. The Copper Mines are located about east of the furnace site, and consist an adit near the creek, and a series of 3 shafts along the line of the reef running roughly s-w to n-e over the crest of the ridge, and mullock associated with the shafts. The main shaft is a three-compartment shaft. There is a collapsed ore bin and shute, and some concrete machinery pads, but no other substantial above- ground remains. Sundown Tin and Copper Mine was listed on the Queensland Heritage Register on