T I T
T I T
( 455 )
and precipitable from this menftruum of a bloodred colour by tindlure of galls.
$. i. Ores.
Sp. I. Titanite. Ruthil, Wern. Ruthile,Broch. Titane oxyde, Hauy. Red Schorl, of theolder mineralogilts.
Its colour is dark blood red, palling into red-dilh brown and copper red. It occurs onlycryftallized. Its primitive form is a (trait prifmwith a fquare bafe. The other forms that itprefents are molt commonly geniculated, thatis, united by one of its extremities with afimilar cryftal, fo that the two together form avery obtufe angle. Sometimes it happens thata cryftal is terminated only by a fmall fragmentof another, giving to it the appearance of animperfedl pyramidal termination. Befides theabove afcertainable forms, capillary cryllals arenot unfrequently met with ; they are eitherfingle, or bundled or grouped together like network, the interlaces being in the form of equi-lateral triangles. The larger cryllals are longi-tudinally ftriated. The principal fradture of thismineral is foliated in two directions, with aluftre brightly fhining, between femi-metallicand adamantine; its crofs fradlure is imper-fedlly conchoidal, palling into uneven, with agliftering luftre. The thin cryllals are (lightlytranllucent, the others are moftly opake. Itshardnefs is nearly equal to that of quartz, butit is brittle and ealily frangible. Sp. gr. 4.1—4-24-
It is infufible without addition before theblowpipe, but with borax it forms a glafs of ahyacinthine red colour, which by expofure tothe external blue flame, becomes fucceffivelyblue, green, and white. When expofed to ahigh h?at in a charcoal crucible it breaks topieces, and becomes of a pale brown colour.
The titanite of Hungary has been analyfedby Klaproth , and appears to be pure oxyd oftitanium mixed with a little fdex ; that fromSpain appears from the fame authority to be atlead equally pure. The titanite of Afchaffen-burg according to Klaproth, and that of Friuli according to Vauquelin , contain a minute por-tion of manganefe and iron.
It occurs near Rofenau in Hungary , and atCajue'o near Buitraio in New Callille in Spain ,implanted in rock cryftal, in a mountain ofgneifs; at St. Gothard , in the cavities of gra-nite mixed with rock-cryftal, adularia, and■chlorite : in the Saltzburg mountains imbeddedin tremolite; near St. Yrieix in la HauteVienne in France , in rounded cryllals difperfed
in an alluvial bed. It has alfo been found atSarapuika in Siberia , and in New Granada inS. America.
Sp. 2. Odlohedrite. Anatafe , Hauy.
This mineral has already been deferibed un-der the name Anatase, which fee.
Sp. 3. Calcareo-filiceous titanite. Tiianit,Klapr. Nigrine, Broch. Titane filiceo-calcaire ,Hauy.
Its colour is brownilh-red, blackilh-brown,yellowilh-brown, and yellowilh-white. It oc-curs maffive, difleminated, and cryftallized.
Its primitive form is a llrait rhomboidal prifm,the alternate angles of which meafure 137 0 and
43/
The other forms that it prefents are,
x. A rhomboidal prifm with dihedral furn-mits, in which the lateral faces are trapeziums,and the terminal ones triangles.
2. The fame with each of the terminal folidangles replaced by two triangular facets, thusmaking the planes of the prifm lengthenedhexagons, while thofe of the fummit confift offour triangular and two pentagonal facets.
The cryllals are fmall and commonly imbed-ded fingly. Its longitudinal fradlure is foliated,pafling into radiated with a gliftening luftre;the crofs fradlure is flat-conchoidal palling intoeven, and has little or no luftre. It is opake,but fometimes tranllucent on the edges. It iseonfiderably hard, but brittle and eafily fran-gible. Sp. gr. 3.48—3.51.
When expofed without addition to the blow-pipe it only Ihews a commencement of fufion;in a clay crucible it undergoes no change at anintenfe heat; but in a charcoal crucible it meltsat a high temperature into a black opake fcoria.
Specimens of this mineral from Paflaw havebeen analyfed by Klaproth , others from Aren-dahl by Abildgaard, and others from St. Go-thard by Cordier, with the following refults,
Klapr. — Abild. — Cord.
33 — 58-74 — 33-3 1 Oxyd of Titanium
35 — 22.c8 — 28. Silex
33 — 20.18 — 32. Lime