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Minerals and Metals in Ancient India v2.c43.s3.t6: Zircon, Garnet and Tourmaline

Minerals and Metals in Ancient India v2.c43.s3.t6

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Zircon, Garnet and Tourmaline

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These three gem-minerals were known in the ancient world but were often confused with each other on account of their similar hardness and due to their occurrence in a wide range of colours, often resembling each other (vide Table 7.2).

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Zircon (hardness 7-1/2) is the orthosilicate of zirconium, ZrSiO₄. Pure zircon is colourless, little iron giving it a colour which is brownish shade of orange, a mixture of red and yellow. Strongly reddish-yellow variety of zircon is known as hyacinth; this contains more iron in the ferric form. Pale straw-yellow or colourless zircon known as jargon contains iron in the ferrous form. Inter-conversion between hyacinth and jargon is possible by heating under oxidising or reducing atmosphere.

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Hyacinth has been often confused with hessonite or cinnamon-stone variety of garnet, Garnet family of minerals has the general formula R₂²⁺R₂³⁺(SiO₄)₃ where R²⁺ and R³⁺ could be any bivalent and trivalent metallic cation respectively. Naturally, a wide range of minerals of diverse colour are possible in the garnet family, and actually exist in nature. Hessonite is calcium-aluminium garnet with some replacements by Fe²⁺ and Fe³⁺. In colour, hessonite resembles cinnamon and the seed of pomegranate or ‘grenat’ (from which the name ‘garnet’ has been derived). A deeper red variety of garnet, now known as ‘almandine’, was christened by Pliny as *carbunculus alabandicus* (from Alabanda in Asia Minor) or *carbunculus* (the name was loosely used to represent diverse red stones).

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Hessonite and hyacinth are so much alike that lot of hessonite, though inferior in brilliance and luster, were bought and sold in the European market as the coveted hyacinth. Similarly, the lighter variety of zircon or jargon from Matura in Sri Lanka often passed as ‘Matura diamond’ on account of its transparency, brilliance and high refractive index.

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The varieties of zircon can be distinguished from other gems through their remarkably high specific gravity (4.61-4.82) and characteristic hardness 7-1/2 which is slightly more than that of garnet (hardness 7-1/4 and sp. gr. 3.6-3.7) and much less than that of diamond (hardness 10 and sp. gr. 3.52). We have mentioned earlier that the heavier or ‘Matura variety of diamond’ was considered to be impure or fake diamond (AM, 49-52); this came from the gem gravel of Sri Lanka as jargon.

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The name zircon came either from jargon (‘the worthless diamond’) or Arabic *zargun* (zar — gold and gun — colour in Persian). The Indian *Ratnaśāstra* texts referred to light yellow jargon as well as reddish-yellow hyacinth variety of Zircon.

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In the pre-Christian era, Kauṭilya mentioned, but did not describe *gomeda* or zircon, excepting bracketing it with *gomūtra* or cow-urine (AS, 2.11.30 and 39). Agastiya *Ratnaparīkṣā* made a complete series of descriptive statements about *gomeda* or zircon (ARP, 82-86; repeated later in *RRS*, 4.54) :

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गोमेदसमरागत्वद् गोमेद रत्नम् उच्यते
सुस्वच्छम् गोजलच्छायम् स्वच्छम् स्निग्धम् समम् गुरु।
. . . मसृणम् दीप्तम् कबद्ध कान्ति अति स्निग्धम्
धवलम् पिंजरम् पीतकाभम् चतुवर्णम् हि गोमेदम्।।
*gomedasamarāgatvād gomeda ratnam ucyate*
*susvaccham gojalacchāyam svaccham snigdham samam guru |*
*.... masṛṇam dīptam kabaddha kānti ati snigdham*
*dhavalam piñjaram pitakābham catuvaṛṇam hi gomedam ||*

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Zircon (*gomeda*) is coloured like cow-flesh (*gomeda*), also like cow-urine. It is transparent, smooth, and very heavy. It may be many-hued (*kabaddha*), white, light yellow or *piñjara* (reddish-yellow, golden, tawny brown); thus, it could have four ‘castes’ (*caturdhā jātiveda* in Agastimata Appendix 4-5 in Finot, p.134).

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*Navaratnaparīkṣā* contains the comparison of zircon with honey and cowurine (NRP, 161): मधुविन्दुसमम् चापि गोमूत्राज्यसमप्रभम् गोमेदकम् madhuvindusamam cāpi gomūtrājyasamaprabham gomedakam

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Bright golden colour hemāraktojvalam of zircon was emphasized in Laghu Ratnaparīkṣā (15). Rayaṇaparikkhā (RYP, 100) compared the colour of zircon with that of indragopa or cochineal insect, and mentioned its sources such as the valley of the Narmadā. The other two sources, mentioned as Sirināthakula and Parevaga country, are not identifiable:

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श्रीनाथकुल परेवग देशेषु तथा नर्मदादीमध्ये।
गोमेद इन्द्रगोपः सुस्निग्धः पाण्डुरः पीतः।।
śrīnāthakula parevaga deśeṣu tathā narmadānadīmadhye |
gomeda indragopaḥ susnigdhaḥ pāṇḍuraḥ pītaḥ ||

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Maṇimālā contained some more statements on gomeda (MM, 330-337), which was stated to be available in the Himālaya and the shore of the Indus (MM, 330). Opinions were divided as to the price of a sterling gomeda, ‘some maintaining it to be double that of a proportionate mass of gold (evidently zircon in this case was made to pass as diamond), some holding it to be equal to that of a vidruma (coral), some to that of cāmāra (bushy tail of Bos Granniens) (MM, 336). Fraudulent jewellers were known to fabricate false gomeda with crystal, just as transparent or light-coloured zircon or gomeda sometimes passed as diamond belonging to one of the four classes or castes (MM, 337).

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During the middle of the seventeenth century AD, Nicols wrote about the availability of zircon in Cannanor, Calicut and several places in the Kerala seacoast.

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Like zircon, garnet has also been widely available in different localities in India, e.g., Sarwar mine in the Kishangarh district in Rajasthan, Kondapalli in the Godavari district, etc. We are not sure whether the ancient gemmologists of India could distinguish between the hyacinth variety of zircon from the hessonite or almandine variety of garnet, both kinds of material occurring widely in India and Sri Lanka, having similar or overlapping colours and not-too-different values of hardness.

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Is Pulaka Garnet?

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The dictionary meaning of pulaka is horripilation, and we have explained earlier that this is a fit description of cat’s eye gem showing chatoyancy. Kautilya mentioned pulaka and śuklapulaka (AS, 2.11.35) which could represent chrysoberyl cat’s eye and quartz cat’s eye; these were later termed as laśunaka (garlic). Neither Kauṭilya nor Varāhamihira (Bṛ. Saṃ. 80.4) described pulaka.

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Śukla (white) pulaka was certainly not the brownish red garnet. Yet Buddhabhaṭṭa used this name to describe something which could be garnet or a chatoyant cat’s eye (RP, 242) :

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गुञ्जान्जन क्षौद्र मृणालवर्ण एते प्रशस्त पुलक प्रतिष्ठितः।
सूत्रैः उपेताः परमाः पवित्रा मांगल्यरूपा बहुरूपचरिताः।।
guñjānjana kṣaudra mṛṇālavarṇa ete praśasta pulaka pratiṣṭitaḥ ।
sūtraiḥ upetāḥ paramāḥ pavitrā māṅgalyarūpā bahurūpacaritāḥ ।।

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Pulaka is of many hues. It could be black and red or black-spotted red like the guñja berry, or like honey or stalk of the lotus. It could also appear threaded, striated and auspicious.

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Later Garuda Purāṇa elaborated the two parts of the description given in RP, 242. In the first part guñjāñjana kṣaudra mṛṇālavarṇa was repeated and additional statements were made gandharva vahni kadali sadṛśa avabhāsaḥ — looks like musk-deer, fire or the plantain tree’ and that the gem is available in Dāsārṇa (Dhasāna in Central India), Mekala mountain (source of the Narmadā) and Vāgadava or Bagdad (GP, 1.77.2 and MM, 430). This description could correspond to garnet.

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Garuda Purāṇa elaborated the second part : śaṅkhābja·bhṛṅgārka vicitravarṇāḥ svacchāḥ māṅgalyayuktā citrā pulakā transparent and like the conch, the lotus, the bee or the sun, threaded or striated (GP, 1.77.3 and MM, 431). The second description matches more with the transparent and light coloured chrysoberyl or quartz of the cat’s eye variety with horripilation or chatoyancy, rather than the dark red coloured garnet. It may be noted that we had referred earlier to the statement in RYP, 100 that the Narmadā Valley abounds in gomeda or zircon having the colour of indragopa or cochineal insect. This could easily pass as guñjāñjana pulaka or garnet.

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It is quite possible that pulaka described in RP, 242 and GP, 1.77.2-3 corresponds not to garnet but to cat’s eye varieties only. Bauer (1968: 492) mentioned that quartz cat’s eye deposits of reddish brown colour (resembling garnet) were available in Quilon, Cochin and in several other places of Malabar coast. This variety of quartz cat’s eye as well as green chrysoberyl cat’s eye were available in Sri Lanka also.

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Similar colours of different varieties of gems often confused the ancient gemmologists, who were not equipped with the knowledge of modern science. Pliny for example, tended to call most red gems as carbunculus, and then subdivided this family into categories: male and female. The former was ruby, and the ‘female’ carbunculus matched with hyacinth zircon or hessonite garnet. This confusion probabaly existed in ancient India too. Reddish garnet was known probabaly by more than one name. Apart from pulaka (which indicated cat’s eye also) the other name for garnet was śikhari. Tagore (1879: 514-15 in Maṇimālā) quoted āraktakāyaṃ śikhari and attributed this to reddish or pale-red cinnamon-stone or hessonite variety of garnet.

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Another gem mineral which has created some confusion is tourmaline. It is like garnet, a group of isomorphous substances with SiO₄ groups (also B₂O₅ groups) and possessing similar hardness (7-1/4) and same range of colour. The chemical formula has been tentatively suggested as H₉Al₃ (B.OH)₂ Si₄O₁₉ in which nine atoms of hydrogen are replaceable by variable amounts of Al, Mg, alkalies and colour-inducing Mn, Fe, Cr, etc. Mn induces the darker red shade, Cr³⁺ and Fe²⁺ green colour and so on. Tourmaline can be black, blue, green, red etc. Usually it is vertically striated and has resinous luster. Its specific gravity varies between 2.9 to 3.3. It is birefringent (two refractive indices) and dichroic (appearing differently coloured when viewed along different crystallographic axes).

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Ancient India was acquainted with the Sri Lankan tourmaline, of yellowish green colour which resembled chrysolite or peridot of lower hardness (6-1/2), and of brown colour which resembled hyacinth variety of zircon. The name ‘tourmaline’ arose from Turamali, the place in Sri Lanka which supplied zircon, and similar gems to Europe during the beginning of the eighteenth century AD.

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We are not certain about the Sanskrit equivalent of tourmaline. Tagore (1879: 514-15) quoted a text: śvetam harinnilam ativa diptam gandhararatnam khalu vajratulyam and translated this as tourmaline (gandharva) which is white, green or blue and bright like lightning. Vajratulya could also mean ‘hard and sparkling like diamond’. It may be recalled that in GP, 1.77.2 the word gandharva appeared along with pulaka and garnet. This has been quoted before. On the other hand, the text of Rasaratnasamuccaya has equated vaikrānta ‘which possesses eight edges, eight facets, six angles, which is smooth, heavy and associated with mixed colours or play or colours’ miśrita varṇe yukta vaikrānta (RRS, 2.53). It was said to resemble vajra and could cut down or deform the metal: vikṛntayati lohāni tena vaikrāntaka smṛtaḥ (RRS, 2.60).

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Tourmaline of course resembles diamond in lustre and high refractive index, but its hardness (7-1/4) is much less than that of diamond (10). We wonder whether blue sapphire (hardness 9) was misunderstood as blue vaikrānta of so-called ‘high hardness’. RRS (2.65-66) mentioned purification of vaikrānta with salty, alkaline and acidic liquids or solutions, and extraction of metal (2.69-71) or sattvapātana from vaikrānta. In this connection we may recall that Kauṭilya mentioned about a metal vaikṛntaka and its ore vaikṛntaka dhātu. We discussed the problematic identity of these two materials, and opined in chapter 5, that the ore could be magnetite and the metal iron. Did the authors of *RRS* equate vaikrānta or black tourmaline with Kauṭilya’s vaikṛntaka dhātu or magnetite, and proceed to extract metal (sattvapātana) from the former?

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