One of a group of specimens illustrating copper smelting - a sample of copper containing sulphur and other gaseous matter, which when fused and setting escapes and throws up metal forming a volcano

One of a collection of raw and manufactured products from the Great Exhibition of 1851 - a sample of peacock ore or sulphuret of copper from the Burra Burra Mines, South Australia

One of a collection of Cape of Good Hope products from the Paris Exhibition, 1867 - a sample of sulphate of copper and iron

One of a group of copper ores and other specimens illustrating the extraction of the metal - a sample of sulphide ore from various mines tributary to Chase Creek, for No. 4 Sulphide Mill, Clifton

One of a group of copper ores and other specimens illustrating the extraction of the metal - a sample of sulphide ore from the Humboldt Group and other mines tributary, for No. 6 Mill at Morenci

One of a group of copper ores and other specimens illustrating the extraction of the metal - a sample of sulphide ore, average smelting grade, from Coronado Mine

One of a group of copper ores and other specimens illustrating the extraction of the metal - a sample of sulphide ore, average smelting grade, from Longfellow Mines

Red sulphur cast of the reverse of the Great Seal of William I (of Scotland), depicting the king as a knight on horseback, c. 1165

Red sulphur cast of the obverse of the Great Seal of Alexander II, depicting the king on his throne, c. 1214

Brown sulphur cast of the reverse of the Great Seal of Alexander III, depicting the king as a knight on horseback, c. 1249

Red sulphur cast of the obverse of the 2nd Great Seal of Alexander III, depicting the king on his throne, c. 1265

Brown sulphur cast of the reverse of the 2nd Great Seal of Alexander III, depicting the king as a knight on horseback, c. 1265

Brown sulphur cast of the obverse of the 1st Great Seal of John I (Balliol), depicting the king on his throne, c. 1292

Brown sulphur cast of the reverse of the 1st Great Seal of John I (Balliol), depicting the king as a knight on horseback, c. 1292

Seal impression in red sulphur, of the reverse of the 1st Great Seal of Robert 1 (Bruce) of Scotland, depicting the king as a knight on horseback, c. 1306

Brown sulphur cast of the reverse of the Great Seal of David II, depicting the king as a knight on horseback, 1329