Crystallography (Prac) Flashcards
Practical Crystallography Revision (Prac only - examples limited to prac samples)
Topaz
(Crystal System, Habit, Forms, Cross Section, Characteristic Features)
Crystal System: Orthorhombic
Habit: Prismatic (usually)
Forms: Prism, Bi-Pyramid, brachy domes, macro domes, macro pinacoid, brachy pinacoid
Cross Section: Lozenge
Characteristic Feature: Perfect Basal Cleavage; Vertical Striations on Prism Faces
Spinel
(Crystal System, Habit, Forms, Cross Section, Characteristic Features)
Crystal System: Cubic (Isometric)
Habit: Equant; Octahedral
Forms: Octahedron; Rhomic dodecahedron
Cross Section: Square
Characteristic features: Commonly shows rotational contact twin on octahedral faces; octahedral form
Danburite
(Crystal System, Habit, Forms, Cross Section, Characteristic Features)
Crystal System: Orthorhombic
Habit: Prismatic
Forms: Macrodomes, brachy dome, bipyramid, basal pinacoid
Cross Section: Lozenge
Characteristic features: Lozenge shape cross section; prominent macro dome face; vertical striations on prism faces.
Garnet
(Crystal System, Habit, Forms, Cross Section, Characteristic Features)
Crystal System: Cubic (Isometric)
Habit: Equant; Blocky; Rhombdodecahedral; Trapezohedral
Forms: Rhombic Dodecahedron; Trapezohedron
Characteristic features: Form, colour and greasy lustre
Ruby
(Crystal System, Habit, Forms, Cross Section, Characteristic Features)
Crystal System: Trigonal
Habit: Tabular
Forms: Prism; Bipyramid; Rhombohedron; basal pinacoid
Characteristic features: Triangular growth hillocks on pinacoid faces; 3-fold symmetry indicated on pinacoid faces
Beryl
(Crystal System, Habit, Forms, Cross Section, Characteristic Features)
Crystal System: Hexagonal
Habit: Prismatic
Forms: Prism; Bipyramid; Basal Pinacoid
Cross Section: Hexagon
Characteristic features:
Aquamarine: Symmetrical etch pits on prism and basal pinacoid faces
Emerald: colour; well-formed prism
Zircon
(Crystal System, Habit, Forms, Cross Section, Characteristic Features)
Crystal System: Tetragonal
Habit: Prismatic
Forms: Prisms; Bi-pyramids
Cross Section: Square
Characteristic features: Sub-adamantine lustre; UV; Heft; Simple contact twin (geniculate)
Diamond
(Crystal System, Habit, Forms, Cross Section, Characteristic Features)
Crystal System: Cubic (Isometric)
Habit: Equant; Octahedral
Forms: Cube; Rhombic Dodecahedron; Octahedron; Hexoctahedron
Characteristic features: Trigons on octahedral faces; heavily etched and rounded faces; adamantine lustre; Rotational contact twin (macle) shows flattened triangular habit and re-entrant angle
Apatite
(Crystal System, Habit, Forms, Cross Section, Characteristic Features)
Crystal System: Hexagonal
Habit: Prismatic
Forms: Prism; Bipyramids; Basal Pinacoid
Cross Section: Hexagon
Characteristic features: Iridescence at internal cracks
Cubic / Isometric System Crystals (Name 3)
Diamond
Spinel
Garnet
Sapphire
(Crystal System, Habit, Forms, Cross Section, Characteristic Features)
Crystal System: Trigonal
Habit: Bipyramidal; Barrel Shape; Dog-tooth
Forms: Bipyramids; rhombohedron; basal pinacoid
Characteristic features: Horizontal striations on bipyramid faces; basal parting; triangular growth hillocks on pinacoid faces
Tourmaline
(Crystal System, Habit, Forms, Cross Section, Characteristic Features)
Crystal System: Trigonal
Habit: Prismatic
Forms: Prisms; Pyramids; Pedion
Characteristic features: vertical striations on prism faces
Quartz
(Crystal System, Habit, Forms, Cross Section, Characteristic Features)
Crystal System: Trigonal
Habit: Prismatic
Forms: Prism; Rhombohedron; Trigonal Bipyramid
Characteristic features: Horizontal striations on prism faces; LH and RH crystal faces
Hexagonal System Crystals (Name 2/3)
Beryl (Emerald / Aquamarine)
Apatite
Trigonal System Crystals (Name 3/4)
Quartz
Tourmaline
Corundum (Ruby/Sapphire)
Tetragonal Crystals (Name 2)
Zircon
Scapolite
Orthorhomic Systems Crystals (Name 2)
Topaz
Danburite
Which crystals and their system have a lozenge shape cross-section?
Topaz
Danburite
Which crystal has perfect basal cleavage?
Topaz (Orthorhombic)
Which crystal can have have dog-tooth shaped crystals?
Sapphire (Trigonal)
Which crystal can have trigons on crystal faces?
Diamond (Cubic)
What are the 7 crystal systems?
Cubic (Isometric); Tetragonal; Hexagonal; Trigonal; Orthorhombic; Monoclinic (not covered in prac); Triclinic (not covered in prac)
What is the crystal system of Topaz?
Orthorhombic
What is the crystal system of Danburite?
Orthorhombic
