English NameCopper Metal
DefinitionTāmra is the end product of the metallurgical process of Copper ore. It is available in the form of wires, sheets or rods of Copper which is produced by an electrolytic process.
SynonymsSamskrta : Sulvaka, Sulva, Surya, Suryasakha, Tamraka, Ravi
Regional NameBangali - Tama, English - Copper, Gujarati - Trāmbu, Tambu, Hindi - Tāmba, Kannada - Tāmbra, Latin - Cuprum, Malayalam - Chembu, Marathi - Tāmbe, Tamil - Chempu (S.F.I.), Telugu - Rāgi, Urdu - Nuhas, Miss, Tāmba (N.F.U.M.)
Origin and occurrence:Tāmra, in native form, occurs as irregular platy dendrites, crystals and compact mass and is most commonly associated with basic extrusive igneous rocks. Such occurrences are very limited. Electrolytically refined Tāmra is produced mainly in smelter/ refinery plants at Khetri in Rajasthan and Maubhandar-Ghatsheela in Jharkhand, where Copper ore occurs in abundance. Native Tāmra is comparatively less pure than electrolytically refined Copper, which contains 99.50% to 100% Cu. Native Tāmra as well as electrolytically refined Copper generally contain trace amounts of Gold, Silver, Zinc, Arsenic, Iron, Bismuth and Antimony.
Physical PropertiesNature : Plates, wires or rods; can be bent by hand, Colour : Copper red, Streak : Copper red, Cleavage : None, Fracture : Hackly, Lustre : Metallic, Tenacity : Malleable, Transparency : Opaque, Hardness : 2.5 to 3.0, Sp. Gr. : 8 to 9
Chemical Properties:Reaction with acids: Take about 5 g of finely powdered (150 mesh) Tāmra in a borosil test tube. Add 10 ml nitric acid. It gets completely dissolved in the acid giving a blue solution. Add an excess of ammonia to this blue solution. The colour of solution changes to deep azure blue. Assay: Tāmra should contain not less than 99.5% Copper (Cu) (Appendix-3.1.9 & 3.2.2). Heavy metals and Arsenic: Tāmra should not contain more than the stated limits for the following: - Lead = 5 ppm, Arsenic = 1 ppm and Cadmium = 5 ppm (Appendix-3.2). Other Elements: May contain the following within ± 20% of the stated limits:- Zinc = 25 ppm, Silver = 10 ppm and Gold = 135 ppb (Appendix-3.1 & 3.2).
ŚodhanaShall not be used in formulations without subjecting it to śodhana. Tāmra is used in the form of bhasma, the details of which are given in the monograph of bhasma.