588 



THE TROPICAL AGRICULTURIST. [Feb. i, 1886. 



wassuggested to us, and which we mentioned in 

 sub itting a specimen to our ever-reliable geological 

 roferemc.Mr. A. Murray, of the Public Works Depart- 

 ment, a gentleman so strangely oveilnuked by the Ex- 

 liibition Committee with reference to their collections 

 of geological and rnineralogical specimens, which 

 lie was perfectly competent to name and classify. 

 Mr. Murray at once recognized the true nature of 

 the crystals and wi'ote : — 



" The geological apecimeus you sent me are very 

 interestuig— what you take to be copper pyrites is 

 really Blue Sjiiinlle, au alumiuate of magnesia, known 

 to occur in crystalline limestone such as your speci- 

 men is." 



Before the receipt of Mr. Murray's letter we 

 had picked out some of the crystals with a pen- 

 knife and finding them translucent we had dis- 

 missed the idea of copper pyrites and we got to 

 reading about lapis lazuli kyanite and topaz. Had 

 we thought of looking into Mr. A. C. Dixon's account 

 of our mountain limestones, in the .Journal of the 

 local branch of the Asiatic Society for 1880, we should 

 have found that the form bearing blue crystals was 

 not so rare as we had deemed. Mr. Dixon re- 

 ported : — " A dolomite occurring at Wai'iapola, on the 

 Matale railway, contains a large amount of blue 

 spinel." In the collection of minerals which ac- 

 companied Mr. Dixon's paper, there were two 

 specimens of spinel, one from Watagama, 

 about half-way between Matale and Kandy, 

 and the other from Ratnapura. Gygax had also 

 supplied a specimen of spinel to the Asiatic Society's 

 Museum, so long ago as 1848. In truth, Ceylon 

 and Siam are recognized as the two great sources 

 of spinel, one of the varieties from our island 

 being named Geylanite, and another Candite for 

 fhe reason thus stated by Tennent :—" Spinel of 

 extremely beautiful colours is found in the bed of 

 the Mahaweliganga, at Kandy, and from the locality 

 it has obtained the name of Cnndite." The 

 origin of the name CeylaniU will be found further 

 on. One of the authorities we consulted stated : — 

 Spinel, a mineral allied to corrundum, consisting 

 chiefly of alumina, with smaller proportions of 

 magnesia, silica and protoxide of iron. It occurs in 

 crystals, which are oiten octohedral and is chiefly 

 found in Ceylon and Siam. Its colours are various : 

 red, blue, green and black. It is much prized as a 

 gem ; red spinels are commoiily called rubies ; the 

 Balaa ruby is a red spinel and a violet coloured spinel 

 is known as Alamandine ruby.' 

 From another we learned that spinel 



Occurs in loose and embedded octohedral crystals. 

 Hardness greater than that of quartz but less than 

 that of corrundum. Colours : red, blue, violet, green, 

 yellow, brown and black. The first most common, 

 transparent, translucent, opaque specific gravity 

 3'5 to3'7. Infusible by the blowpipe; the red varieties 

 are rendered black and become opaque by exposure 

 to it, but ou cooling at first of a fine green by trans- 

 mitted light, then nearly colourless and at last 

 become again red. Ceylon and Siam in isolated and 

 Toiled crystals in the beds of rivers. Embedded m 

 carbonate of lime in North America and Sweden. 

 Red : — 8i-47 alumina ; 8-78 magnesia and 618 chromic 

 acid. 

 Blce: — Silica 5-48 



Alumina 72''25 



Magnesia \i6S 



Protoxide of iron 4'26 



It will be noticed that red spinel contains a good 

 deal of chromic acid to wliicli we suppose it owes its 

 colour? The blue, it will be seen, has a good deal 

 less alumina in its composition but more magnesia, 

 with silica and protoxide of iron, against the 

 chromic acid of the red variety which includes the 

 spinel vuby. Of course, if fine rolled crystals of 

 spinel are found in the rivers of Ceylon, the chances 

 of finding largo unworn crystals in the parent 



I rook are all the greater. Mr. Kellow will no doubt 

 I search for large, clear, flawless crystals, and we 

 1 should say that where such crystals are not pre- 

 t sent, slabs of the rock for tables and mantlepieces, 

 and pieces for paper weights, &e., would be likely to 

 take a beautiful polish. Curiously enough, one of the 

 traditions of Nuwara filiya is that the late Mr. 

 Wm. Kellow stated that while digging potatoes ho 

 had found a large mass of sapphire which he put 

 aside, and which when he again looked for it, 

 it could not be found. No doubt, the "sapphire" 

 was a piece of limestone, blue and radiant- with 

 spinel crystals. Spinel occurs, of course, in other 

 primary rocks besides the crystallized limestone, and 

 we suppose it is Davy who is quoted by Pridham 

 to the effect that " spinel is comparatively rare, 

 though some small and most beautiful crystals of 

 it are found in the interior, and it is found in 

 specimens of clay iron ore in parts of the Central 

 Province where gneiss prevails." No doubt, the red 

 or ruby form was referred to. In the Manual of 

 the Geology of India, we find it stated that 



The spinel ruby differs from the true oriental 

 (corundum) ruby in composition by containing a 

 varying percentage of magnesia, and the maguesium is 

 occasionally replaced by iron, calcium, manganese, or 

 ziuo. The mineral therefore iucludes many virieties, 

 some of which are opaque and unsuitiible for jewellery. 

 The spinel rubv is distinguinheil from the corundum 

 ruby by being of inferior hardness and, when crystalUne, 

 by its octohelral form. 



There is little or no information as to the occur- 

 rence of the spinel inljieninsular India. Its occurrence 

 in Mysore has been asserted, but apparently requires 

 authentic confirmation. There are several" countries 

 beyond the confines of peninsular India where the 

 balas ruby has beeu regularly miued for. 

 And then a hst of the extra-Indian countries is 

 given, commencing with Afghanistan, where spinel 

 is found in a matrix of crystalline micaceous lime- 

 stone. Then comes a curious statement : — 



Badakshan. — The balas ruby mines of Cadaksbau are 

 situated on the banks of the Shigbuan, a tributary 

 of the Oxns. Tb -y have beeu known by reputation 

 for very many centuries, and the name hala^ is derived 

 from B.ilakshan, another form of writing the name of 

 the country or from Baikh the capital (own. This 

 may possibly be the origin of the common nii.stake 

 made in English works on precious stones, namely, that 

 these mines are situated in Balochistau! Marco Polo 

 states that in his time the mines were wholly in the 

 hands of he King, who kept up the value of the 

 stones by only pt-rmitting a limited number to be ex- 

 ported. C')louel Ynle remarks upon this that the 

 monopoly has beeu continued to the present day. 

 When Mnrad Beg of Kundnz conquered Badakshan he 

 was so (hsgnsted with the poor outturn of the mines 

 that he abandoned working them, and the papulation 

 of the neighbourhood were sold as slaves. In 1866 

 the reigning Mir had one of the mines opened at 

 the request of Pundit Manphul, but without much 

 result. Wood, in 1S37, attempted to visit these 

 raiuea but failed : however, he gives a short ac- 

 count of thein. The matrix, he states, is a red 

 sandstone, or a limestone largely impregnated with 

 magnesia ; most probably it is a liuiestoue, as such 

 appears to bo the usual matrix. The galleries were 

 easily made and numerous, but the frequent influx 

 of water caused much trouble. 



Upper Burma. — It is stated that a large propor- 

 tion of the rubies which are sold in Burma are reallv 

 only spmel, this mineral apparently occurring also 

 in the already described "em sands. When the crys- 

 talline form !s obscure the two stones may be dis- 

 tinguished either by their hardness, specific gravity, 

 or their refractory powers. Although of less value 

 the spinel rabies arc lari,'ely used in jewellerv. 



The Rev. F. Mason, wlio givfs some interesting 

 information on this subject, states that be had a 

 stone, which every native who had seen it, — and 



