Greenstone

“ It consists in the use of the term greenstone, which has been applied by them to some of the dark varieties of the syenitic granite. It has appeared to me, as I have remarked in the body of the paper, that these varieties of syenitic granite were distinguishable from true greenstone by the presence of quartz, and that however minute their texture, and apparently uniform the white ingredient, it always contained that mineral in conspicuous proportion, while in greenstone, a common member of the trap family, it was rarely present, and might, when present, be considered as accidental. ”

“ Greenstone possesses a fine texture. It is hard and tough and forms an ideal material in many respects, but it has this one drawback, it does contain a great many structural planes, and the axe sooner or later comes to grief. How rarely a greenstone axe is well finished, the aborigine knew all too well that in some unexpected hour it would break. If ninety per cent of our Wisconsin axes are made of igneous rocks, about eight per cent perhaps are made of metamorphic rocks, while the remaining two per cent are formed from sedimentary rocks of various types, chiefly sandstone and limestone. ”

“ The greenstone, so far as we found it, is about the smallest of the shingle, and, although it is obtained readily enough, it is advisable for one to keep what he gets to himself, and not give it to his neighbour, as he may do so, and then search for the next two hours to discover that there is nothing green to be seen, except in his own organs of vision. ”

“ The rock occurring in greatest abundance, and which is probably the fundamental bed, is a porphyry, the basis of which in general is claystone, which in many places passes into felspar, in others becomes a distinct greenstone. Numerous veins of calcareous spar traverse it in different directions, and I am lately informed, that very beautiful examples of veins of greenstone of contemporaneous formation with the rock itself, have been discovered in the greenstone. Upon the porphyry rests a bed of trap tuff, upon this other beds of the two rocks repose, that at the summit being porphyry. ”

“ A convenient term of this kind is greenstone, which merely indicates that the ferromagnesian minerals are prominent and usually give a greenish or dark cast to the rock. The greenstones embrace the diorites, dolerites, some of the gabbros and the basalts, and may even extend to the peridotites and some of the more hornblendic of the granitoid rocks. Another convenient name is trap, which may be used for any dark, heavy igneous rock. ”

“ The rest of the island seems to be generally formed of great intersecting ridges of greenstone, enclosing plains or valleys composed of the palæozoic formation. Some of the more massive greenstones are evidently anterior to the palæozoic formation, as sections may be seen in which horizontal beds of sandstone abut against cliffs of greenstone, or even repose upon steps and ledges of that rock. In other cases, however, sandstones of the palæozoic formation appear to be capped by immense masses of greenstone, and they are certainly often broken through by basaltic and other igneous rocks. ”

“ Greenstone slate? occurs in horizontal beds on the north shore, eight or nine miles to the westward of Dease River: [Pg 267] and at Limestone Point, [22] about twenty miles from the river, a small range of hills terminates on the borders of the lake, in shelving, broken cliffs, about two hundred feet high. These cliffs consist chiefly of nearly compact light-coloured dolomite, interstratified with greenstone, and a brownish-red limestone, such as occurs in the hills at the mouth of the Dease River. ”

“ This greenstone decomposes into a thick bed of red clay; it is much intersected by fissures or cleavage planes at all angles, whose surfaces are covered with a shining polished superficial layer; like the fissures in the cleavage planes of the gneiss granite of Kinchinjhow, whose adjacent surfaces are coated with a glassy waved layer of hornblende. ”

“ Reference has been made to the patient industry of the Maori race. A supreme example of this is that every man had his tikki, or image of a little idol made of greenstone, which was hung round his neck. Now, this New Zealand greenstone is one of the hardest objects in nature, and yet it is worn down without metals into these quaint figures. On an average it took ten years to make one, and it was rubbed down from a chunk of stone into an image by the constant friction of a woman's foot. ”

“ On approaching the foot of the hills on the road from Perth to York, we pass at once from the horizontal brown sandstone to a steep slope of granite, above this to another of greenstone, and then to granite again. The surface of this plateau of rock, here about 800 feet above the sea, was gently undulating, covered with one wide forest of a large eucalyptus, called here mahogany. ”

“ So that we would be well out of the sphere of the companions of the man who carried the greenstone blade, we worked our way for about one hundred yards through the leafy maze before attempting to search for it, and that search proved a long and tiresome one. It is impossible to describe the network of wanton vegetation through which we struggled during the hot afternoon. Every kind of shrub and tree was woven into an ungodly tangle by the crawling, leaping vines that shut out the sky and made it impossible to see a person standing only a few feet away. ”

“ The only locality known to the ancient Maori where greenstone was to be found was on the west coast of the South Island of New Zealand. It could therefore be obtained by the tribes of the North only by barter or as booty after a successful war. ”

“ Of this greenstone there are several varieties. Sometimes it is of a dark bluish-green colour, passing into iron-grey; is massive, glimmering, of a coarse-grained uneven fracture, and breaks into irregular rather blunt-edged fragments; it gives a pale greenish-grey streak, is considerably heavy and difficultly frangible. When immersed in an acid an effervescence is perceived from various parts of its surface: by examination with a lens it appears to be composed of hornblende and felspar, with a little calcareous spar and mica. ”

“ Limestone is dug near Hag Gate, Gale Hall, and Ardale water, &c. These limestone and coal measures occupy no guest breadth, and run north and south in a line nearly parallel to the ranges of greenstone and slate, being generally in contact with the former of these substances. Their extent longitudinally is from Melmerby Lane End to the Ardale water. From the latter stream southwards to the village of Murton, the red sandstone abuts for the most part against the greenstone. ”

“ These thinner beds are separated from each other by laminæ, of a clay slate, very much confounded with the sandstone, and those two substances alternate frequently and irregularly, till they approach the thicker beds which lie in contact with the greenstone. As they approximate to it they become more indurated, and assume a texture approaching to that of hornstone. ”

“ In spite of the longing desire of the northern Maori to enrich themselves with the treasures of greenstone which existed on the west coast of the South Island, the serious obstacles which beset the approach to that region deterred them from making the attempt to get there, and they had to content themselves with what they were able to acquire from their fellow countrymen in the south, in exchange for mats and canoes and such other manufactures as their southern neighbours were willing to accept. ”

“ It seems to have been formed, not by striking off flakes, but by notching it. It is a hard, dense, black greenstone (like aphanite) , and how it was notched I cannot imagine. Its weight is one pound one and a half ounces. Its length is six inches and a half, its breadth two inches and a quarter, and its thickness one inch and a half. In section it is lenticular. The cutting edge has symmetrical curves, and the lower part is highly polished. There is a hollow on one side of the upper part of the stone, made probably for attaching the handle with security. ”

“ Greenstone is an excellent rock, and has a fine surface, but it is unmanageable. The greyer granites may often be used with good effect, as well as the coarse porphyries, when the grey is to be particularly warm. ”

“ I have seen another of this form, but of flint (41/2 inches) , with the sides much rounded, so as to be almost oval, found near Eastbourne, where also this form has occurred in greenstone. The late Mr. H. Durden, of Blandford, had a celt of greenstone of this form 43/8 inches long, found at Tarrant Launceston, Dorset. Many of the celts found in India are of this type.
Fig. 70.—Seamer, Yorkshire. 1/2 A shorter form, which also seems to be most prevalent in Yorkshire, is represented in Fig. 70. The specimen figured is from Seamer, formed of greenstone, and belongs to the Greenwell Collection. ”

“ The mass of greenstone nearest to Cambridge is found in the toadstone beds of Derbyshire, to some specimens of which the pebble No. 6, bears a close resemblance. Few of these pebbles weigh less than 8 ounces. ”

“ It was only rarely that the Maori used tools or weapons shaped like our axes, and the reason is obvious. The greenstone never being drilled or cut to receive the tool handle, an axe with its edge parallel with the line of the handle was an impossibility, and an axe-like tool made by lashing the stone head to the side of the handle would be clumsy and ineffective. ”

“ Having described as far as I know the extent of the slate and greenstone, with the subordinate rocks and dykes that accompany them, I will now consider the strata by which they are encircled, and which on the east side are widely different from those on the west.
On the east side beneath the outcrop of the great limestone series of Cross Fell, (of which Mr. Winch gives the thickness at 450 fathoms,) the old red sandstone, in the form of a conglomerate, is regularly interposed between the lowest stratum of the above series and the slate, with no appearance of any great derangement. ”

“ The sheets of greenstone that spread from below the Rowley Hills, through the centre of the district, up to Wednesfield and Bentley, always run pretty nearly in the same beds, at whatever depth those beds may be found, and however they may be broken by faults. This shows that the "green rock" is itself cut through by the faults and thrown up or down by them, as the case may be, exactly as the Coal-measures are affected by them. ”

“ When the condition of the stone is of that intermediate nature which renders its precise place uncertain, the modified term of syenitic greenstone is easily applied. In difficult cases where these rocks are still more varied in their composition, and in all others where a multiplication of terms would lead to an unbounded and unnecessary nomenclature, it will even be preferable to distinguish the variation from the more rigid form by a detailed description rather than to encumber the science with a useless neology. ”

“ In attempting to descend the creek from our last encampment, we found the valley so obstructed with fragments of greenstone as to be wholly impassable. We accordingly ascended into the plain; and continuing along on the brink of the precipice, arrived in a few hours at a point where the substratum of sandstone emerges to light at the base of an inconsiderable hill. It is a fine gray sandstone, having an argillaceous cement, and its lamina are so nearly horizontal, that their inclination is not manifest to the eye. ”

“ The slaty clay, with subordinate beds of ironstone, which lies above the greenstone, differs but little from the common slaty clay of the coal formation. This however is by no means the case with the three beds that lie immediately below the greenstone, namely, the indurated sandstone, the carbonaceous slaty clay, and the blind coal. ”

“ The principal varieties of trappean rock are basalt, green stone, and trachyte. In basalt, augite, or, in some cases, hornblende, is the predominant mineral. It is a heavy, close-grained rock, of a black or dark brown color. Greenstone differs from basalt in containing a much larger proportion of felspar. Its structure is more granular, and frequently it assumes so much of the crystalline form as to pass insensibly into syenite or granite. ”

“ In passing through the village just named, I observed in the street a small block of stone differing in appearance from any I had found previously, and upon examination I found it to be granite, a rock I had searched for before without success, and indeed this is the only place where I saw an unstratified rock in the whole district, the porphyry and greenstone which accompany the grauwacke formation in Devonshire being wholly wanting here. ”

“ Beds of sand, sandstone, limestone, belonging to the Cretaceous Period. The name is given to these beds because they often, but not always, contain an abundance of green earth or chlorite scattered through the substance of the sandstone, limestone, &c.
Greenstone. A variety of trap, composed of hornblende and felspar.
Greywacké. Grauwacke, a German name, generally adopted by geologists for some of the most ancient fossiliferous strata. The rock is very often of a gray color ”

“ Most of them stand entirely isolated; others in groups and ranges, but all are distinct hills, with unconnected bases. The surface of the country generally, and more especially in the immediate vicinity of these hills, is strewed with fragments of compact or porphyritic greenstone. ”