21. The relationship between otin that of sialon and silicon nitride is similar to that between brass and pure copper . 22. It decided on clad coinage, with copper nickel faces and a pure copper core, as the most desirable replacement material. 23. It is pure copper , Siegel says, and indeed it looks and feels like the copper in a freshly minted penny. 24. Although they were pure copper , removing the masses took a great deal of effort, and was sometimes not even profitable. 25. These coins were made of pure copper , which is very soft . Consequently, there are very few in existence today. 26. In terms of chemical composition, analysis of pure copper belonging to group of copper-bearing sandstone, indicates Kargaly as a possible source. 27. When the cells are electrified, the anodes slowly dissolve, freeing copper ions that are deposited on the cathode as 99.99-percent-pure copper . 28. Their weight in pure copper should be so close to the intrinsic value of the material that counterfeiting would be uneconomic. 29. He envisioned an ore body several thousand feet deep, some veins of almost pure copper and hundreds of millions of dollars. 30. There would be two coins of pure copper : a d�cimo de real and its half, legal tender to 2 reales.
