Semester 1 2018 2019 KristalMineral GS 1126 2

Semester 1, 2018 -2019 Kristal-Mineral GS 1126 - 2 SKS teori by: DR. hill. gendoet hartono Selasa&Jumat-jam 07. 30 – 09. 10 & jam 09. 15 – 10. 55

SILABUS TGS 7113 KRISTALOGRAFI - MINERALOGI (2 SKS) Minggu III Minggu IV Minggu VIII PENDAHULUAN PENGENALAN KRISTAL SISTEM KRISTAL SIFAT/KARAKTERISTIK KRISTAL VS MINERAL PEMBENTUKAN & MODIFIKASI MINERAL Aspek Kimia PEMBENTUKAN & MODIFIKASI MINERAL Aspek Fisik UJIAN TENGAH SEMESTER

SISTEM KRISTAL 7 Sistem Kristal Pembagian utama dlm klasifikasi kristal-kristal menurut bentuknya : Kubik, Tetragonal, Hexagonal, Trigonal, Ortorombik, Monoklinik & Triklinik

Dasar penggolongan sistem kristal : • Jumlah sumbu kristalografi v kristal bersumbu tiga dan empat • Letak atau posisi sumbu kristalografi v semua sumbu saling tegak lurus v salah satu sumbu tidak tegak lurus v ketiganya saling tegak lurus • Perbandingan panjang dari sumbu-sumbu kristalografi v tiga sumbu mempunyai parameter yang sama v dua sumbu parameternya sama dan satu diantaranya berbeda § Nilai sumbu c atau sumbu vertikal Sumbu Kristal : garis bayangan, lurus, yg menembus kristal (bidang-bidang muka kristal) dan melalui pusat kristal

Crystal System (Shape) • Different minerals have different crystal shapes

c+ a- b- b+ a+ c- • 3 sumbu saling tegak lurus a┴b; b┴c; c┴a a=b=c • sumbu a+ dibuat 30 o terhadap b • parameter a dibuat 1/3 b (b = c = 3 a)

Mineral Identification Basics • ISOMETRIC CRYSTALS a 3 ISOMETRIC a 2 In this crystal system there are 3 axes. Each has the same length (as indicated by the same letter “a”). They all meet at mutual 90 o angles in the center of the crystal. a 1 ISOMETRIC Basic Cube Crystals in this system are typically blocky or ball-like.

Cara Menggambar: Ð a- / b+ = 300 a : b¯: c = 1 : 3

Mineral Identification Basics • ISOMETRIC CRYSTALS Within this ISOMETRIC crystal model is the OCTAHEDRAL crystal form (yellow) and the TETRAHEDRAL crystal form (shown by the black lines). ISOMETRIC Crystal Model

Mineral Identification Basics • ISOMETRIC CRYSTALS a 3 a 2 a 1 ISOMETRIC - Basic Cube Fluorite cube with crystal axes

Mineral Identification Basics • ISOMETRIC BASIC CRYSTAL SHAPES Spinel Octahedron Garnet Trapezohedron Fluorite Cube Garnet - Dodecahedron Pyrite Cube with Pyritohedron Striations

Sistem Tetragonal • Mempunyai 3 sumbu kristal yg tegak lurus a b c • a = b sama c berlainan • kadang ditulis: • a 1=a 2 c 17

Cara menggambar: Ð a + / b-- = 30 o a: b: c=1: 3: 6

Mineral Identification Basics • TETRAGONAL CRYSTALS TETRAGONAL c Two equal, horizontal, mutually perpendicular axes (a 1, a 2) a 1 a 2 Vertical axis (c) is perpendicular to the horizontal axes and is of a different length. c TETRAGONAL Crystal Axes a 1 a 2 This is an Alternative Crystal Axes

Mineral Identification Basics • TETRAGONAL CRYSTALS TETRAGONAL This model shows a tetragonal PRISM enclosing a DIPYRAMID. TETRAGONAL Crystal Model

Mineral Identification Basics • TETRAGONAL CRYSTALS WULFENITE Same crystal seen edge on.

Mineral Identification Basics • TETRAGONAL CRYSTALS This is the same Apophyllite crystal looking down the “c” axis. APOPHYLLITE on Stilbite The red square shows the position of the pinacoid (perpendicular to the “c” axis).

See u next week….