Causing the crystal of tourmaline to revolve round the tube, with its axis perpendicular to the illuminating beam, the quantity of light that reached the eye was in all its positions a maximum.
This name comes from a Cingalese word (turamali) which was applied to the first Tourmaline gems sent from Ceylon to Holland.
I have shown how one of the most remarkable properties of Tourmaline was discovered by children.
The form of crystals of Tourmaline is usually that of a three-sided prism.
This has been true of the black Tourmaline shown in the accompanying plate.
It is known that black Tourmaline has an excess of iron, the red and green an excess of sodium and lithium, and the yellow and brown an excess of magnesium in their composition.
Both black and brown Tourmaline are usually opaque, and hence have no value as gems.
In composition Tourmaline is a complex silicate chiefly of aluminum and boron.
In its opaque form, colored either black or brown, Tourmaline is a comparatively common mineral.
The red Tourmaline (Rubellite) from California, illustrated in the accompanying plate, is found in San Diego County of that State.
The rose color of the Tourmaline contrasting with the violet of the lepidolite makes an object which is quite a favorite with mineral fanciers, although the former is not sufficiently transparent to be used as a gem.
So to the present day, although Tourmaline is considerably used in jewelry, it is rarely ever called by that name.
Anyone can repeat their observation by gently heating crystals or even fragments of Tourmaline and applying them to bits of paper.
As either tourmaline or emerald might thus exhibit dichroism (the tourmaline more strongly, however, than the emerald) one more test was tried to finally decide the matter.
The stronger dichroism of the tourmaline frequently reveals itself to the naked eye, and there is usually one direction or position in which the color of the stone is very inferior to its color in the opposite direction or position.
Tourmaline of the reddish variety (rubellite) is seldom of a deep red.
Some of the Maine tourmaline is of a delightful, slightly bluish-green tint that almost approaches emerald.
Connecticut green tourmaline tends more to the dark yellowish green, and Ceylon tourmaline to the olive green.
The dichroism of tourmaline is stronger than that of ruby and more obvious to the unaided eye.
The luster of olivine (whether of the peridot shade or not) is oily, and this may serve to distinguish it from tourmaline (which it may resemble in color).
These double images might have been produced by tourmaline as well as by emerald.
As far as color goes the material might be yellow quartz, or yellow beryl, or yellow zircon, or yellow tourmaline (Ceylon type).
Some of the Madagascar tourmaline is of a fine brownish red, almost as deep as a light garnet, and much clearer than most garnet.
The tourmaline is a most complex substance; almost every stone obtained has a different composition, some varying but slightly, with mere traces of certain constituents which other stones possess in a perceptible degree.
It is also interesting to note that if thetourmaline is not warmed so high as to reach a temperature of 50° F.
If, then, a little of this now golden-coloured mixture is gently dusted over the surface of the tourmaline or other stone possessing electric polarity, a most interesting change is at once apparent.
But as the tourmaline cools yet further, though but a fraction of a degree, the magnetic properties change; the positive pole becomes the negative, the negative having changed to the positive.
It will be remembered that in Hogarth's "Rake's Progress," the youth is too engrossed in the changing wonders of a tourmaline to notice the entrance of the officers come to arrest him.
If it is suspended on a silken thread from a glass rod or other non-conducting support in a similar manner to the pith ball, the tourmaline will be found to have become an excellent magnet.
Taking the tourmaline as an example of the pyro-electric minerals, we find that when this is heated to between 50° F.
The granite, which is intruded through the Eocene beds, is associated with a pegmatite containing tourmaline and cassiterite.
The wire framework behaves towards the electric waves exactly as a plate of tourmaline does to waves of light.
An attempt to make the tourmaline locket serve as a key to the enigma promised well at first, but could not quite be induced to fit the lock after all.
A kind of granite from Luxullian, Cornwall, characterized by the presence of radiating groups of minute tourmaline crystals.
A variety of tourmaline varying in color from a pale rose to a deep ruby, and containing lithium.
In the tourmaline granites prisms of black schorl occur either singly or in stellate groups.
Hydrofluoric and boric emanations exert a profound influence on granitic rocks; their felspar is resolved into aggregates of kaolin, muscovite and quartz; tourmaline appears, largely replacing the brown mica; topaz also is not uncommon.
Tourmaline may be brown, yellow or blue, and often the same crystal shows zones of different colours.
Veins of quartz, tourmaline and chlorite may traverse the granite, containing tinstone often in workable quantities.
Brewster found that even powdered tourmaline exhibited opposite electrifications on the opposite extremities of each tiny particle, causing the latter to act, so far as attractions and repulsions went, as infinitesimal magnets.
The Abbe Hauey discovered that fragments of tourmaline crystal exhibited opposite electrifications on opposite extremities of their lines of cleavage.
Defn: A variety of tourmaline of an indigo-blue color.
Defn: A variety oftourmaline varying in color from a pale rose to a deep ruby, and containing lithium.
Note: Crystals of tourmaline when heated exhibit electric polarity (see Pyroelectric, n.
Tourmaline is also used in the form of a polariscope called tourmaline tongs.
Defn: A kind of granite from Luxullian, Cornwall, characterized by the presence of radiating groups of minute tourmaline crystals.
In the Grevillian collection purchased many years ago by government for the British Museum, there is a fine specimen of red tourmaline valued at 500l.
Crystal of tourmaline slit (parallel to the axis) into four plates, which when ground and polished, may be used for the polarization of light.
Majority 201 At the last election Tourmaline had had a majority of six hundred over his Conservative opponent, so that there had been a turnover of about four hundred voters.
But a few of the wisest amongst them shook their heads, for they knew too well that "Tourmaline the Traitor and Turncoat" (as the posters described him) was by no means alone in his discontent with the tendencies of the party.
The tourmaline appears to have been brought to Europe from Ceylon by the Dutch about the end of the seventeenth century, and was exhibited as a curiosity on account of its pyro-electric properties.
A variety of tourmaline varying in color from a pale rose-red to a deep ruby, and containing lithium.
One very interesting result of Kirchoff's law is the emission of polarized light by glowing tourmaline and by one or two other crystal when they are heated to incandescence.
Since the absorbing power of tourmaline is different for the two components, the emissive power should also be different, and that component which was most absorbed should be radiated most strongly.
Sapphire, ruby, emerald, and tourmaline result also from contact metamorphism of sediments in the vicinity of igneous rocks.
Tourmaline is a complex hydrous silicate of aluminum and boron, with varying amounts of magnesium, iron, and alkalies.
Tourmaline probably always originated as a high temperature mineral, especially as crystals in granites and related rocks and in certain metamorphic rocks which have been subjected to high temperature and pressure.
And on viewing these through a tourmaline or a Nicol’s prism, as in the experiment with the two tourmalines, the images will become alternately visible and invisible, just as was then the case with the entire mass of light.
In the above experiments the lower prism or tourmaline is called the polarizer, because it polarizes the light, and the upper is called the analyzer, because it analyzes or tests the light altered by the former.
The light emergent from the tourmaline is polarized.
Now suppose, when the two plates are crossed, that we interpose a third plate of tourmaline between them, with its axis oblique to both.
For a long time investigators were compelled to employ plates of tourmaline for this purpose, and the progress they made with so defective a means of inquiry is astonishing.
But now I turn the film so as to render its directions of vibration oblique to the two tourmaline axes; then, you see it exercises the power, demonstrated in the last lecture, of partially restoring the light.
Making the plate of tourmaline vertical, and reflecting it as before, it is the light of the upper image that is quenched; the side image now shows the green.
Placing the tourmaline in front of the aperture, two images of the crystal will also be obtained; but now let us reason out beforehand what is to be expected from this experiment.
Hence we may infer that one image of the tourmaline will show the ordinary green light of the crystal, while the other image will be black.
It was at this angle that the image of the tourmaline was completely quenched in our former experiment.
It is plain that, by means either of the tourmaline or the reflecting glass, we can determine in a moment the direction of vibration in any polarized beam.
Thus, by pure reasoning, we infer that the interposition of a third plate of tourmaline will in part abolish the darkness produced by the perpendicular crossing of the other two plates.
Let us now return to a single plate; and here let me say that it is on the green light transmitted by the tourmaline that you are to fix your attention.
The tourmaline was all ready, but up to one o'clock not a trace of the sun could be seen.
Moreover, in tourmaline the dichroism is strongly marked, whereas in jargoon it is remarkably feeble.
I asked, remembering the loveliness of that face with its red and wilful lips and its ever-changing tourmaline eyes.
I could see the Scotch-granite look that came into the thick-lashed tourmaline eyes.
And she has tourmaline eyes, with reddish hazel specks in an iris of opaque blue, and small white teeth and lips with a telltale curve of wilfulness about them.
There were sizeable yields of freshwater pearls in Tennessee, turquoise in Arizona and Nevada, tourmaline in Maine, and tourmaline, kunzite, and garnet in California.
But surely that is all wrong," said Tourmaline gravely.
Instead of a silken gown furbelowed like all the others they had seen women wear in this land, Tourmaline was dressed in a severely plain robe of coarse pink cloth much resembling bedticking.
The twelve Counselors then voted, and when the vote was counted, Tourmaline announced that six had voted to allow the strangers to remain and six to toss them over the bushes.
Tourmaline in an awed voice, and the Witch beside her nodded and said, "Fairies of the sky.
Tourmaline hastened away to her father's house to put on a beautiful gown all covered with flounces and ribbons, for she was glad to be relieved of the duties of the Queen and was eager to be gaily dressed and one of the people again.
Tourmaline smiled and shook her head, while all the Counselors murmured their protests.
The case is decided," announced Tourmaline in a clear, cold voice.
The Pink Band played as loud as it could--in order that the travelers might hear it as long as possible--and Rosalie and Coralie and Tourmaline threw kisses to their vanishing friends as long as they remained in sight.
I did not choose to be the Queen," answeredTourmaline simply.
I know of one witch," saidTourmaline thoughtfully, "but she is not very obliging.
Without hesitation Tourmaline removed the rose-gold circlet with its glittering jewel and handed it to Polychrome, who turned and placed it upon Trot's brow.
She is the sole Ruler of our country, so the word of Tourmaline is the Law of the Land.
She further ordered a pink statue of Tourmaline to be set up in the Court, and also a pink statue of herself, so that the record of all the rulers of the Pinkies should be complete.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "tourmaline" in a variety of sentences. We hope that you will now be able to make sentences using this word.
