Elements of mineralogy, crystallography and blowpipe analysis from a practical standpoint .. . is made the vertical,c, and the third the clino, a,dips downward from back tofront. The acute angle be-tween the vertical and clinoaxis is called All that has been said as to series under the orthorhombic sys-tem on p. 48 may be repeated here. The axes are understood tobe fixed with one definite value for /5 for all forms of the series. PRISMATIC CLASS. 5. No. 28. Holohedry, Liebisch. No. 28. Normal Group, Dana. All the common monoclinic minerals occur in crystals sym-metrical to one plane
Elements of mineralogy, crystallography and blowpipe analysis from a practical standpoint .. . is made the vertical,c, and the third the clino, a,dips downward from back tofront. The acute angle be-tween the vertical and clinoaxis is called All that has been said as to series under the orthorhombic sys-tem on p. 48 may be repeated here. The axes are understood tobe fixed with one definite value for /5 for all forms of the series. PRISMATIC CLASS. 5. No. 28. Holohedry, Liebisch. No. 28. Normal Group, Dana. All the common monoclinic minerals occur in crystals sym-metrical to one plane and to one axis normal to the plane, General Form or Hemi Pyramid. Composed of four faces each intersecting all the axes in dis-tances not simple multiples of each other. For any symbol twoindependent forms result, each of four faces. The four in Fig. 207 constitute the so-called positive hemi pyramid, those in Fig. 208 the negative. *Also called Hemiprismatic, Zwei-und-eingliedridge, Monoclinohedral, Clinorhom-bic, Monosymmetric. 56 CRYSTALLOGRAPHY. Fig. 206. Fig. 207. Fig. Just as in the orthorhombic system the faces of a hemi pyra-mid may have the unit intercepts or any one or two of the inter-cepts may be simple multiples of those of the unit face. To dis-tinguish the possible varieties the following names and symbolsare needed: Positive Unit Series Pyramid,Negative Unit Series Pyramid,Positive Ortho Pyramid,Negative Ortho Pyramid,Positive Clino Pyramid,Negative Clino Pyramid, Limit Forms. The general form will, for certain positions of the faces, pass intolimit forms as follows : Weiss. Dana. Miller. ?\- a?mc + m \ Ml} — a?inc — m ^ hhl \ -\- a :nb: inc -\- m — n \ hkl ^ — a:nb: vie — 711 —n -{ hkl} + na? mc -\- m — n \ khl\ — na:b : mc — m - h \ khl} Each face parallel to two axes. Weiss. Dana. Nauman. I. Basal Pinacoid. oa a : oa b : c 0 { 001 )? 2. Ortho Pinacoid. a : (X b : ca c i — l { TOO \ 3. Clino Pinacoid. ca a? ca c i — i \ 0
Size: 2205px × 1133px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyorkdvannostran
