Minerals and Metals in Ancient India v2.c43.s1.t1.5

v2.c43.s1.t1.5

| Name English/Sanskrit | Colour | Hardness (Moh's Scale) | Reasons for Non-white Colour |
| Aquamarine/ pāribhadra | Faint blue to bluish green | 7-¾ | Bluish tinge due to iron. |
| Zircon/gomed | Cow-flesh/ colour | 7-½ | Pure zircon ZrSiO₄ is colourless. Reddish-yellow colour of Hyacinth is due to Fe³⁺, decolourised on reduction to Fe²⁺. |
| Garnet/tāmrya or tāmḍi | Various colours | 7-¼ | Family of minerals M₃²⁺ . M₂³⁺ . (SiO₄)₃. Colour depends upon chemical composition. Hessonite is confused with Hyacinth. Colour due to iron. |
| Tourmaline/ vaikrānta | Various colours | 7-¼ | H₉Al₃(B.OH)₂Si₄O₁₉ pure tourmaline is light coloured. Fe²⁺ and Cr³⁺ make it dark green, Mg makes it brown and Mn dark red. |
| Quartz/sphatika | Colourless | 7 | Pure SiO₂ is colourless. Yellow citrine due to iron; green chrysoprase due to nickel, violet amethyst due to manganese etc. |
| Agate/akik Carnelian/ Rudhirākhya | Light colour Red | 6-½ | Hydrated SiO₂ is colourless. Hydrated ferric oxide as impurity makes it brown or yellow. Heating causes dehydration and ferric oxide gives red colour to carnelian. |
| Olivine/Chrysolite/ Peridot/puttikā/ jabarjad | Bottle green | 6-½ | Pure Mg₂SiO₄ is colourless. Replacement of part of MgO by ferrous oxide makes it yellowish green. Mn²⁺, Ni²⁺ further change the colour. |
| Orthoclase/Feldspar Moonstone/candra-kānta; Sunstone suryakānta | Opalescent; play of Colour | 6 | Interference of light from thin tayers. |
| Jade/pilu | White green black | 5-½ - 7 | Green due to Mn and Cr and Fe²⁺. Black due to Fe³⁺. |
| Turquoise | Blue | 6 | The mineral is a derivative for ortho-phosphoric acid, the hydrogen atoms replaced by radicals such as Al(OH)₂ Fe(OH)₂ (providing green tinge) and Cu(OH) (providing intense blue colour). |