Upload
galang
View
233
Download
0
Embed Size (px)
Citation preview
8/19/2019 GD 4 mineral-batuan.pdf
1/74
Geologi Dasar(MGD 301)
Materi 4
Program Studi Teknik Perminyakan
Fakultas Teknologi Mineral dan EnergiUniversitas Trisakti2009
8/19/2019 GD 4 mineral-batuan.pdf
2/74
Quiz - 15 menit! 1. Tektonik lempeng merupakan proses yang
menjelaskan fenomena - fenomena alam dibumi,
sebutkan dan jelaskan 3 bentuk interaksi antarlempeng bumi.
! 2. Sebutkan bagian bagian bumi berdasarkankomposisinya
! 3. Sebutkan slogan uniformatarianisme
! 4. Sebutkan min. 3 hukum steno
! 5. Berapa panjang jari - jari bumi?
2
8/19/2019 GD 4 mineral-batuan.pdf
3/74
Materi 4- PENGERTIAN GEOLOGI
- BUMI SEBAGAI PLANET- LITHOSFERA - MINERAL- BATUAN : BT, BEKU
BT SEDIMENBT, METAMORP
8/19/2019 GD 4 mineral-batuan.pdf
4/74
MINERAL
! Dalam pengertian geologi mineral adalah zat atau benda yangterbentuk oleh proses alam, biasanya bersifat padat, tersusun dari
komposisi kimiawi tertentu serta mempunyai sifat fisik yang
tertentu pula
! Mineral terbentuk dari atom-atom serta molekul-molekul dari
berbagai unsur kimia, dimana atom-atom tersebut tersusun dalam
suatu pola yang teratur
! Keteraturan dari rangkaian atom ini menjadikan mineral
mempunyai sifat dalam yang teratur
8/19/2019 GD 4 mineral-batuan.pdf
5/74
From: Plummer et al.
Mineral: A naturally occurring inorganic element or compound
having orderly internal structure and characteristic chemical
composition, crystal form, and physical properties.
8/19/2019 GD 4 mineral-batuan.pdf
6/74
Groups or Families
Periods
8/19/2019 GD 4 mineral-batuan.pdf
7/74
Unsur Mineral! Di alam ini terdapat sekitar 2000 jenis mineral yang telah diketahui.
Mineral-mineral tersebut ada yang tersusun oleh unsur tunggal,adapula yang terdapat sebagai persenyawaan.
! Yang terdiri dari unsur tunggal misalnya ;Au = aurum = emas
Ag = Argentum = perak Cu = Cuprum = tembagaC = Carbon = dalam bentuk allotropi
= Keadaan dimana Dua zat atau lebih mempunyai sifat kimiawi samatetapi berbeda dalam sifat fisiknya) berbentuk intan atau grafit
8/19/2019 GD 4 mineral-batuan.pdf
8/74
Graphite & CalciteNatural Octahedral Diamond
3 mm
From: http://www.phy.mtu.edu/~jaszczak/diamond.html
8/19/2019 GD 4 mineral-batuan.pdf
9/74
Mineral yang merupakan Senyawa
Kimia! CaCO3 = KALSIT
! CaSO4 2H2O = GYPSUM
! SiO2 = KWARSA! NaCl = HALIT
! KAlSi3O8 = FELSPAR ORTOKLAS
!
Fe3O4 = MAGNETIT! CuFeS2 = CHALCOPYRIT
8/19/2019 GD 4 mineral-batuan.pdf
10/74Halite Atomic Structure
Chemical Formula: NaCl
Note Cubic Symmetry and Closest Packing
Chemical compound: Two or more elements joined together by
a chemical bond. Most minerals are composed of at least two
elements.
8/19/2019 GD 4 mineral-batuan.pdf
11/74
Rocks versus Minerals
Feldspar: NaAlSi3O8 - KAlSi3O8
Quartz: SiO2
Biotite: KMg3AlSi3O10(OH)2 -
KFe3AlSi3O10(OH)2
Granite rock type
Rock: an aggregate of one or more
minerals; in this case there are three
minerals present.
8/19/2019 GD 4 mineral-batuan.pdf
12/74
Contoh Batuan Kerak Benua bagian bawah
Granulite
Gambar menunjukkan sayatan tipis batuan dalam miroskopis/petrografi dan
contoh ambilan tangan granulite (hand
specimen)
8/19/2019 GD 4 mineral-batuan.pdf
13/74
Contoh Mineral Pembentuk Batuan
diantaranya memiliki nilai ekonomis untuk
komoditi karena unsur yang dikandungnya Analcime Andalusite Anhydrite
AntimonyAragonite Arsenopyrite Augite Barite Beryl
Bornite
Brazilianite Brookite Calcite CassiteriteChalcocite
Chalcopyrite Chrysoberyl
Corundum
Cryptomelane Cuprite Cyanotrichite
Diopside
Dioptase
Epidote Feldspar Ferberite
Danburite
8/19/2019 GD 4 mineral-batuan.pdf
14/74
Perhiasan yang dipergunakan adalah preciousgems/jewelry yang berasal dari logam dan
mineral di bagian interior bumi dan mutiara daridasar samudra
Gems & Jewelry
8/19/2019 GD 4 mineral-batuan.pdf
15/74
Sifat Fisik Mineral dan Batuan
!Unsur-unsur penyusunan bumi/
batuan terjadi dalam bentukmineral : secara langsung mineral
dapat dikenal dari sifat fisiknya antara lain :
8/19/2019 GD 4 mineral-batuan.pdf
16/74
1. Bentuk Kristal (Crystal Form)Mineral dan Batuan
- Umumnya mineral mempunyai
bentuk kristal dan hanya sedikityang berbentuk amorf (antara lain
kalsedon dan opal, variasi mineralsilikat).
8/19/2019 GD 4 mineral-batuan.pdf
17/74
1 - 5 mm
From: http://www.its.caltech.edu/~atomic/snowcry
Hexagonal Symmetry
Oddly, ice is less dense than liquid water,
hence it floats and lakes freeze from the
top down!
8/19/2019 GD 4 mineral-batuan.pdf
18/74
8/19/2019 GD 4 mineral-batuan.pdf
19/74
BENTUK DASAR DARI KRISTAL :
! - ISOMETRIK - CONTOH : GALENA, HALITE &INTAN.
!
- TETRAGONAL - CONTOH : ZIRCON.! - HEKSAGONAL - CONTOH : KUARSA.
! - ORTHOROMBIK - CONTOH : TOPAS.
! - MONOKLINIK - CONTOH : GITHOKLAS
! - TRIKLINIK - CONTOH : PlAGIOKLAS
! DAN MASIH BANYAK VARIASI BENTUK KRISTALLAINNYA.
8/19/2019 GD 4 mineral-batuan.pdf
20/74
Silicon Tetrahedron: SiO4 (net -4 charge)
8/19/2019 GD 4 mineral-batuan.pdf
21/74
Olivine Structure: (Mg,Fe)2SiO
4
8/19/2019 GD 4 mineral-batuan.pdf
22/74
Quartz Interfacial Angles
Perfectly
ProportionedCrystals
Misshapen
Crystals
Steno’s Law: Crystal face internal angles remain constant!
8/19/2019 GD 4 mineral-batuan.pdf
23/74
Macroscopic Forms and Microscopic Blocks
Cubes
Rhombs
Macroscopic
Crystal Forms
8/19/2019 GD 4 mineral-batuan.pdf
24/74
Crystal Forms: Quartz
8/19/2019 GD 4 mineral-batuan.pdf
25/74
2. SISTIM BELAHAN (CLEAVAGE )
! Umumnya setiap mineral akan pecah menurut pola tertentu
sesuai sistim belahan mineral tersebut, sistim belahan tersebut
disebut 'cleavage'.
! Contoh : mineral mika mempunyai sistim belahan yang baik,yaitu ia akan pecah menurut bidang cleavege berlembar-lembar.
! Ada beberapa meneral mempunyai belahan dua arah ialah
kelompok mineral pyroxene; dengan sistim kedua belahan
membentuk sudut 90 °! meneral amphibol membentuk sudut 55 °
! Sistim belahan melengkung (conchoidal) seperti terdapat pada
meneral glass dan kalsedon.
8/19/2019 GD 4 mineral-batuan.pdf
26/74
Planer Cleavage in Mica
8/19/2019 GD 4 mineral-batuan.pdf
27/74
Weak Bonding Yields Planer Cleavage
8/19/2019 GD 4 mineral-batuan.pdf
28/74
Amphibole Cleavage ~120/60°
8/19/2019 GD 4 mineral-batuan.pdf
29/74
Rhombohedral Cleavage in Calcite
8/19/2019 GD 4 mineral-batuan.pdf
30/74
Conchoidal Fracture in Glass
8/19/2019 GD 4 mineral-batuan.pdf
31/74
Chrysotile Asbestos
Belongs to the Serpentine mineral family -
hydrated ferromagnesian silicate.
8/19/2019 GD 4 mineral-batuan.pdf
32/74
3. Dera at Kekerasan Hardness
! Kekerasan • suatu ketahanan terhadap goresanoleh benda lain kekerasan ini relatif sifatnya.
! STANDARD KEKERASAN DARI MOHS
8/19/2019 GD 4 mineral-batuan.pdf
33/74
8/19/2019 GD 4 mineral-batuan.pdf
34/74
The Physical Properties of Minerals (cont.)
! Fracture
! Specific Gravity
! Special Properties
! Other Properties
! Chemical Tests
8/19/2019 GD 4 mineral-batuan.pdf
35/74
Physical properties of minerals
! Based on the principles discussed during thelast lecture and above, we now know thatminerals are composed of atoms, arranged in a
specific order, with a well defined chemicalcomposition. We might expect then that themicroscopic variations in bond environmentdiscussed above, will also be manifested inmacroscopic physical and chemicalproperties. This is indeed the case.
8/19/2019 GD 4 mineral-batuan.pdf
36/74
Important Physical Properties I! Luster - This property describes the appearance of
reflected light from the mineral's surface. Nonmetallic
minerals are described using the following terms:
vitreous, pearly, silky, resinous, and earthy.
8/19/2019 GD 4 mineral-batuan.pdf
37/74
Important Physical Properties II! Color - Although an obvious feature, it is often
unreliable to use to determine the type of mineral.
! Color arises due to electronic transitions, often of trace
constituents, in the visible range of the EM spectrum.For example, quartz is found in a variety of colors.
! Color of a mineral may be quite diagnostic for thetrace element and coordination number of its
bonding environment.
8/19/2019 GD 4 mineral-batuan.pdf
38/74
http://www.nmnh.si.edu/minsci/hope
8/19/2019 GD 4 mineral-batuan.pdf
39/74
Important Physical Properties III! Streak - The color of a mineral in its powdered
form; obtained by rubbing the mineral against anunglazed porcelain plate.
! Streak is usually less variable than color.
! Useful for distinguishing between minerals with
metallic luster.
8/19/2019 GD 4 mineral-batuan.pdf
40/74
Density and Specific Gravity
! Density - Defined as the mass divided by thevolume and normally designated by the Greekletter, rho, !.
!
! =
mass/volume; SI units: kg/m3
or kg m-3
, butgeologists often use g/cm3 as the unit of choice.
! Specific Gravity - Ratio of the mass of a substanceto the mass of an equal volume of water. Note that
!water = 1 g cm
-3
. S.G. is unitless.! Examples - quartz (SiO2) has a S.G. of 2.65 while
galena (PbS) has a S.G. of 7.5 and gold (Au) has aS.G. of 19.3.
C l d
8/19/2019 GD 4 mineral-batuan.pdf
41/74
Color and Density! Two broad categories are ferromagnesian and nonferromagnesian silicates , which
simply means iron and magnesian bearing or not. The presence or absence of Fe and Mgstrongly affects the external appearance (color) and density of the minerals.
! Ferromagnesian silicates - dark color, density range from 3.2 - 3.6 g/cc! Olivine - high T, low silica rocks; comprises over 50% of upper mantle! Pyroxenes - high T, low silica rocks
! Amphiboles - esp. hornblende; moderate T, higher silica rocks
! Mica - esp. biotite; moderate T, higher silica rocks
! Garnet - common metamorphic mineral
! Nonferromagnesian silicates - light color, density close to 2.7 g/cc! Mica - exp. muscovite; moderate T, higher silica rocks! Feldspars - plagioclase and orthoclase; most common mineral in crust; form over a
wide range of temperatures and melt compositions
! Quartz - low T, high silica rocks; extremely stable at surface, hence it tends to be amajor component in sedimentary rocks.
! Clay - esp. kaolinite; different types found in different soils
8/19/2019 GD 4 mineral-batuan.pdf
42/74
8/19/2019 GD 4 mineral-batuan.pdf
43/74
From http://www.geo.wvu.edu/~lang/Geol284/Min8IgFels
8/19/2019 GD 4 mineral-batuan.pdf
44/74
Zoning in Plagioclase Feldspar
Ca-rich core
Na-rich rim
8/19/2019 GD 4 mineral-batuan.pdf
45/74
Note complex zoning pattern:
Ca content increases , then
decreases from core to rim.
Can interpret these chemical
data as indicating influx of
Ca-rich magma (basalt) into
a pre-existing magma chamber
prior to eruption!
From: Zellmer et al., J. Pet. 2003
Ca increases
Ca decreases
8/19/2019 GD 4 mineral-batuan.pdf
46/74
Important Physical Properties IV! Crystal form or habit - The external
morphology of crystals generally reflect the
internal arrangement of their constituent atoms.
This can be obscured, however, if the mineral
crystallized in an environment that did not allow it
to grow without significant interaction with other
crystals (even of the same mineral).
8/19/2019 GD 4 mineral-batuan.pdf
47/74
Chrysotile Asbestos
Belongs to the Serpentine mineral family -
hydrated ferromagnesian silicate.
E i Cl
8/19/2019 GD 4 mineral-batuan.pdf
48/74
Expansive Clays
8/19/2019 GD 4 mineral-batuan.pdf
49/74
Crystal Forms: Quartz
8/19/2019 GD 4 mineral-batuan.pdf
50/74
Feldspar
8/19/2019 GD 4 mineral-batuan.pdf
51/74
Intergrown cubic crystals of fluorite
Quartz Interfacial Angles
8/19/2019 GD 4 mineral-batuan.pdf
52/74
Quartz Interfacial Angles
Perfectly
ProportionedCrystals
Misshapen
Crystals
Steno’s Law: Crystal face internal angles remain constant!
Macroscopic Forms and Microscopic Blocks
8/19/2019 GD 4 mineral-batuan.pdf
53/74
Macroscopic Forms and Microscopic Blocks
Cubes
Rhombs
Macroscopic
Crystal Forms
Unit Cells and Crystal Structure
8/19/2019 GD 4 mineral-batuan.pdf
54/74
Unit Cells and Crystal StructureCubic unit cell:
smallest repeatable unit
8/19/2019 GD 4 mineral-batuan.pdf
55/74
Important Physical Properties V! Hardness - This is the resistance of the mineral
to abrasion or scratching. This property doesn'tvary greatly from sample to sample of the samemineral, and thus is highly diagnostic. It also is adirect reflection of the bonding type and internalatomic arrangement. A value is obtained by
comparing the mineral to a standard scaledevised by Moh , which is comprised of 10minerals ranging in hardness from talc (softest) todiamond (hardest).
8/19/2019 GD 4 mineral-batuan.pdf
56/74
8/19/2019 GD 4 mineral-batuan.pdf
57/74
Graphite & CalciteNatural Octahedral Diamond
3 mm
From: http://www.phy.mtu.edu/~jaszczak/diamond.html
8/19/2019 GD 4 mineral-batuan.pdf
58/74
From: http://www.molecules.org/elements.html#dia
Hardness: 10 Hardness: 1-2
8/19/2019 GD 4 mineral-batuan.pdf
59/74
Fingernail Hardness (2.5) Scratches Gypsum (2)
8/19/2019 GD 4 mineral-batuan.pdf
60/74
Important Physical Properties VI! Cleavage - Orientation and number of planes of
weakness within a mineral. Directly reflects the
orientation of weak bonds within the crystalstructure. This feature is also highly diagnostic.
! Fracture - This describes how a mineral breaks if
it is not along well defined planes. In minerals
with low symmetry and highly interconnected
atomic networks, irregular fracture is common.
Planer Cleavage in Mica
8/19/2019 GD 4 mineral-batuan.pdf
61/74
g
8/19/2019 GD 4 mineral-batuan.pdf
62/74
Weak Bonding Yields Planer Cleavage
Amphibole Cleavage ~120/60°
8/19/2019 GD 4 mineral-batuan.pdf
63/74
Amphibole Cleavage ~120/60
Rhombohedral Cleavage in Calcite
8/19/2019 GD 4 mineral-batuan.pdf
64/74
g
Conchoidal Fracture in Glass
8/19/2019 GD 4 mineral-batuan.pdf
65/74
Conchoidal Fracture in Glass
S i l d Oth P ti
8/19/2019 GD 4 mineral-batuan.pdf
66/74
Special and Other Properties! Striations - Commonly found on plagioclase
feldspar. Straight, parallel lines on one or more ofthe cleavage planes caused by mineral twinning.
! Magnetism - Property of a substance such that itwill spontaneous orient itself within a magneticfield. Magnetite (Fe3O4) has this property and it
can be used to distinguish it from other non-magnetite iron oxides, such as hematite (Fe2O3).
! Double Refraction - Seen in calcite crystals.Light is split or refracted into two componentsgiving rise to two distinct images.
8/19/2019 GD 4 mineral-batuan.pdf
67/74
Plagioclasestriations
8/19/2019 GD 4 mineral-batuan.pdf
68/74
Calcite Double Refraction
X ray diffraction: Laue
8/19/2019 GD 4 mineral-batuan.pdf
69/74
X-ray diffraction: Lauephotographic method
8/19/2019 GD 4 mineral-batuan.pdf
70/74
From: http://www.geology.wisc.edu/~g203/xray.
8/19/2019 GD 4 mineral-batuan.pdf
71/74
From: http://www.geology.fau.edu/course_info/fall02/gly4200/X-R
8/19/2019 GD 4 mineral-batuan.pdf
72/74
Formula:Ca10(Mg,Fe)2Al4Si9O34(OH)4System: TetragonalHardness: 61⁄2
http://www.mindat.org/min-4223.html
Modern Crystal Structure Determinations
8/19/2019 GD 4 mineral-batuan.pdf
73/74
Modern Crystal Structure Determinations
! Get a compositional determination using the electron microprobe.! Determine space group from Precession and or Weissenberg photos.
! Measure x-ray intensities with automated diffractometer.
! Use Fourier analysis to derive electron density maps and locate
particular atoms in positions consistent with the space group.
! Calculate what the pattern should look like for your derived structure(both positions and intensities for all reflections).
! Compare calculated and observed intensities and calculate the percent
disagreement - the residual or error R.
! 20 years ago an R or 10% was good using film techniques.
! Now R should approach 4% for a convincingly good structure
determination.
8/19/2019 GD 4 mineral-batuan.pdf
74/74
Terima kasih
Pustaka dan Acuan :
- Prodi Teknik Geologi FTKE Usakti
- Museum Geologi- Pusat Survei Geologi- Pusat Lingkungan Geologi- Pusat Vulkanologi & Mitigasi Bencana Geologi- Berbagai Situs Internet