Page:Encyclopædia Britannica, Ninth Edition, v. 16.djvu/433

Rh MINERALOGY 415 552. HYDROPHITE, (Mg, Fe) 4 Si 3 Massive and fibrous. H. =3 to 4 ; G. = 2 65. Mountain-green to blue-black ; streak paler. C.c. : silica 36 2, magnesia 21 1, protoxide of iron 227, water 16. Taberg in Sweden, New York. 553. VILLARSITE, 2MgoSi + H-. Right prismatic ; crystals P, OP, meeting at 136 32, often twins in triple combination; also granular. H. =3 ; G. =2 9 to 3. Trans lucent. Greenish to greyish yellow. C.c.: silica 39 6, magnesia 47 4, protoxide of iron 3 6, water 5 - 8. Totaig, Ross-shire ; Traver- sella, Piedmont ; Forez, France. 554. PYKALLOLITE. Oblique prismatic, C 72 56 ; columnar and granular. Cl. basic and hemiJomatie, meeting at 94 36 ; fracture splintery ; brittle. H. =3 5 to 4 ; G. =2 6. Translucent on edges ; resinous. Greenish to yellow-grey. C.c.: silicate of magnesia and water. Storard in Finland. 555. DERMATINE, (% F Eenifonn ; stalactitic ; fracture conchoidal ; brittle. H. =2 5; G. =2 1. Resinous. Blackish green ; streak yellow. Does not adhere to tongue. C.c.: silica 38, magnesia 22, protoxide of iron 12, water 23. Waldheim in Saxony. 556. CHLOROPH.EITE, RSi + R s 8i 3 + 4H- . Massive, rarely reniform. Coating or filling up geodes in amyg- daloidal cavities. H. = 1 &quot;5 ; G. = 2 &quot;02 to 2 &quot;3. Sectile ; fracture con choidal. On first exposure transparent and olive-green to orange- yellow, but soon changes to black and opaque, splitting in so doing. Vitreous to shining. B. B. melts to a black glass. C.c.: silica 36 2, alumina 8 &quot;9, peroxide of iron 13 8, protoxide of iron 2 4, lime 3 8, magnesia 10, water 24 8. Rum and Canna in the Hebrides, Giant s Causeway. The original mineral from Rum has 22 8 iron peroxide and no alumina. 557. FORCHIIAMMERITE, FeSi + 6H . Granular massive. Subresinous to dull. Dark green. H. =2; G. = 1 8. C.c. : silica 32 8, protoxide of iron 21 - 6, magnesia 3 &quot;4, water 42 2. Faroes. 558. KIRWANITE. Fills druses in amygdaloids with divergent sheaf-like crystals. H. =2:G. =2 9. Opaque. Olive-green to dark green. C.c.: silica 40 5, alumina 11 1, protoxide of iron 23 9, lime 19 8, water 4 4. Loch Baa in Mull ; Mourne Mountains in Ireland. 559. GLAUCONITE. Round grains. Dull resinous. Light green. C.c.: silicate of protoxide of iron and potash. Ashgrove near Elgin ; greensand of England, France, Germany, and America. 560. CELADONITE, 3RSi 2 + R a Massive, forming crusts, as of agates. Earthy, sectile. H. =1 to 2; G. =2 6 to 2 8. Opaque, shining. Bright green. Feels ereasy. C.c.: silica 54, alumina 3 8, ferric oxide 11 9, ferrous oxide 5 4, magnesia 6 8, potash 7 9, water 10. Orkney, Rum, and Fifeshire in Scotland. Giant s Causeway, Verona, Faroes, Iceland, Cyprus, Bohemia. 561. STILPNOMELANE, 2(Fe, Mg)S i + A-lS i + 2H. Massive or radiating-foliated. One cl. perfect ; brittle. H. =3 to 4; G. =3to3 4. Opaque ; vitreous to pearly. Greenish black. C.c.: 45 3 silica, 6 9 alumina, 38 &quot;3 iron protoxide (with 2 to 3 magnesia), and 9 &quot;5 water. Zuckmantel in Silesia and &quot;Weilburg in Nassau. 562. CHAMOISITE. Oolitic and massive. H. =3; G. = 3 to 3 - 4. Greenish grey to black; streak paler. C.c.: silica 14 3, alumina 7 8, protoxide of iron 60 5, water 17 4. Chamoison (or Chamoson) in Valais, the Vosges. Berthierinc has 75 protoxide of iron and 5 of water ; Moselle. AUGITE AND HORNBLENDE GROUP. 1 Hornblende and augite rather represent groups of mineral sub stances tban single species. They are best distinguished when imperfectly formed, by the cleavage and angles of the prisms. 563. ENSTATITE (Ghladnitc), MgS i. Hornblende and augite agree so closely in crystalline forms and chemical com- iV-J LO O &amp;lt;J- t). lllUUgU WIU punscao il 121 BTa||Q jmiuild Ml tlicil &amp;gt;tlliv.ai risms, yet these differ in angular dimensions : hornblende 124 12, augite 87&quot; . They also occur in distinct geognostic positions : hornblende in rocks con taining quartz or free silica, and mostly with minerals that are neutral compounds of silica, as orthoclase and albite ; augite in rocks that do not contain free silica, and mostly with minerals that are not neutral silicates, as labradorite, olivine, and leucite. Hence there are two distinct series of massive or igneous rocks : the hornblende series, including granite, syenite, diorite, diorite-porphyry, and red porphyry ; and the augite series or hyp .rsthene rock, gabbro, dolerite, ncpheline rock, augite- porphyry, and leucite-porphyry. Right prismatic. ooP 92 to 93 ; crystals copoo (n), &amp;lt;*IV&amp;gt; (b), 00 P (7), iPoo (*), fp&quot;oo (3), if oo (4), IP ( T ) (fig. 497). Usually imbedded, or indis tinct granular masses. Cl. macrodiagonal very perfect, prismatic ooP distinct, brachy- diagonal imperfect. H. =5 5; G. =3 1 to 3 3. Translucent throughout, or only on the edges ; vitreous or pearly on the more perfect cleavage- planes. Colourless, greyish or greenish white, yellowish, or brown. Not affected by acids. B.B. almost infusible. Fig. 497. C.c.: 60 silica and 40 magnesia, but with 6 to 8 iron protoxide, 1 to 2 alumina, and 1 or 2 water. In olivine and serpentine rocks in Moravia, the Harz (Baste), and the Pyrenees. 564. BRONZITE (Schiller Spar, Baslite), (Mg, Fe)Si. Right prismatic. ooP 94; only granular and foliated. Cl. brachydiagonal perfect, prismatic less so ; fracture uneven, splin tery. H. =4 to 5; G. =3 to 3 5. Translucent on thin edges; metallic pearly. Green, inclining to yellow or brown. Imper fectly sol. in h. acid, wholly in s. acid. B.B. becomes magnetic, and fuses in very thin splinters. C.c.: 43 silica, 26 magnesia, 27 lime, 7 4 iron protoxide, 3 3 iron peroxide, 2 4 chrome oxide, 17 alumina, and 12 4 water. Bastitc is possibly altered enstatite. Belhelvie and Black Dog in Aberdeenshire, Baste, Tyrol, Baireuth, Styria. 565. PAULITE (Ilypcrsthene), (Fe, Mg)Si. Right prismatic. ooP ( m ) 93 30, P2 (c), 2P2 (i), $P$ (u), oo^2 (?i), 4 Poo (h), ooPoo (a), oofoo (b), Po, 2Poo (d). Granular or disseminated. Cl. brachydiagonal very perfect, prismatic ooP distinct, macrodiagonal very imperfect. H. =6; G. = 3 3 to 3 4. Opaque or translucent on thin edges ; vitreous or resinous, but metallic pearly on the cleavage planes, of which one is copper-coloured to violet or silvery. Pitch - black and greyish black ; streak greenish grey or pinchbeck-brown, inclining to copper-red*. Not affected by acids. B.B. melts more or Fig. 498. fig- 499. less easily to a greenish black glass, often magnetic. C.c. : gene rally 46 to 58 silica, to 4 alumina, 11 to 26 magnesia, 1 to 5 lime, 13 to 34 iron protoxide, to 6 manganese protoxide. Portsoy and Craig Buroch in Banffshire, Barra Hill in Aberdeeushire, Paul s Island, Labrador, and Greenland. Crystals occur in sanadine bombs at Lake Laach (AmUystegite), and in meteorites of Brei ten- bach. Hypersthene rock in Norway, Elfdal in Sweden, Cornwall (?), the Harz, and Canada. Chemically enstatite and paulite pass into one another ; the essential difference is that the axial dispersion is uniformly p &amp;lt; v in the former, and the opposite in the latter. 566. &quot;WOLLASTONITE ( Tabular Spar], CaS i . Oblique prismatic, C 84 30 . &amp;lt;xP 87 18, OP (it or h }, ccPco (cor 2^, oo P| (z) 110 7, ooP c 2 (x or e&quot;) 51, - Poo (v) 44 27 , |Poo (a) 69 56 (fig. 500). Rarefy crystallized, mostly broad* prismatic or laminar. Frequently fibrous. Cl. along OP and ooPoo perfect, but planes uneven or rough ; meet at 95 23 . H. =4-5 to 5 ; G. =2 8 to 2 9. Translucent ; Fig. 500. vitreous or pearly on cleavage. White, inclining to grey, yellow, red, or brown ; streak white.