JEO253-Min-Pet Assoc. Prof. Meral Dogan Dr. Dogan’s homepage Lectures 3 Jeoloji Muhendisligi...

JEO253-Min-PetAssoc. Prof. Meral Dogan

Dr. Dogan’s homepageLectures 3

Jeoloji MuhendisligiJeoloji Muhendisligi

Office:Office: 213 213

Office Hours:Office Hours:

Office Phone:Office Phone: 297 77 28297 77 28

Email Address:Email Address: medogan@hacettepe.edu.tr

Lab Syllibus

Lab #1: Measurement of Physical Properties of Minerals.Lab #2: Introduction to the lattice, unit cell, and Miller indices. Crystal systems, classes, and forms. Lab #3: Crystal systems and crystal classes (continued).Lab #4, 5 and 6: Tectosilicates, Phyllosilicates, Inosilicates, Cyclosilicates, Sorosilicates, and Nesosilicates

Lab #7: Carbonates, Halides, Phosphates, Sulfates carbonatesLab #8: Native elements, oxydes and hydroxytes

Lab #9: Magmatic rocksLab #10: Magmatic rocksLab #11: Sedimentary rocksLab #12: Metamorphic rocks

Mineral idendification

Renk-Color Parlaklık-Luster Transparency (or diaphaneity) Kristal sistemleri-Crystal Systems Olusum formlari-Technical Crystal Habits Descriptive Crystal Habits Ikizlenme-Twinning Dilinim-Cleavage Kırılma-Fracture Sertlik-Hardness Specific Gravity Cizgi rengi-Streak Birlikte bulundugu mineraller-Associated Minerals

Color

Usually, we notice the color of a mineral first. Some minerals are easily identified by color because they are never any other color. For example, malachite is always green.

Keep in mind, however, that color by itself isn't enough to identify a mineral. Chemical impurities can change the color of a mineral without changing its basic make-up. For example, quartz in its purest form is colorless and clear as glass. Quartz with traces of iron becomes violet (amethyst). With traces of manganese, it turns pink (rose quartz). If quartz is exposed to radiation, it turns brown (smoky quartz).

Kuvars-quartz (SiO2)

Fluorit (CaF2)

labrodorite

color

çizgi rengi-Some minerals leave a streak similar to their natural color, such as cinnabar

and azurite

Cinnabar Azurite

American Museum of Natural History

The terms used to describe luster (parlaklık)

(Metalik) Metallic -- example: gold ) (Camsı)Vitreous (glassy) -- example: quartz, tourmaline (Işıltılı) Adamantine (brilliant) -- example: diamond ) (Reçine) Resinous (like resin or sap from a tree) -- example:

sphalerite ) (Yağsı) Greasy or waxy -- example: turquoise) (İncimsi) Pearly -- example: talc) (İpeksi) Silky -- example: asbestos) (Toprağımsı) Dull or earthy -- example: bauxite)

Metallic -high reflectivity like metal

Galen (PbS)Sulfit

Dull/earthy -shown by finely crystallized minerals

Hematit (Fe2O3)Oksit

Mohs' Hardness Scale

1-Talc 2-Gypsum3-Calcite4-Fluorite5-Apatite6-Orthoclase Steel  file7-Quartz8-Topaz 9-Corundum 10-Diamond

Gypsum (CaSO4. 2H2O)

JipsSulfat

Calcite-CaCO3

Crystal(smooth faces)

Elmas-Diamond

CrystalReflection

Common Objects and Their Hardness Values

2.5 Fingernail 3.5 Penny 5.5 Glass 6.5 Steel knife

An unknown sample can not be scratched by your fingernail (2.5) but it can be scratched by a penny (3.5), then it's hardness is between 2.5 and 3.5. An example of a mineral that has a hardness between 2.5 and 3.5 is calcite (3).

Specific Gravity

is a special case of relative density defined as the ratio of the density of a given substance, to the density of water when both substances are at the same temperature.

Substances with a specific gravity greater than 1 are more dense than water, and those with a specific gravity of less than 1 are less dense than water.

MineralsDensitySpecific gravity

sulfur, graphite light 1-2gypsum, quartz medium 2-3fluorite, beryl medium -heavy

3-4corundum, most metal oxides heavy 4-6native gold, platinum heaviest 19

Ağır mineraller-Heaviest mineral

Gold

Kristal sekilleri-Crystal forms

Cubic tetragonal hexagonal

Tuz-Halite (salt) (NaCl)

Cubic (intergrown)

Pirit-Pyrite (FeS)

cubic

Işınsal-Radiating habit

marcasite

Klivaj-Dilinim (Cleavages (images web site))

Fracture describes how a mineral breaks when broken contrary to its natural cleavage

planes.

Chonchoidal fracture (quartz) is a smooth curved fracture with concentric ridges of the type shown by glass.

fibrous or splintery (tremolite),

Hackley (copper), is jagged fracture with sharp edges. Irregular

Parting in Minerals

Parting is a property that often gets confused with cleavage. There is good reason for that. Parting is a break along

structural planes and is parallel to a possible face, just like cleavage. A good example is pyrite. However, parting differs from cleavage in some important ways.

It can not be found in every specimen as is true of cleavage for most every cleavable mineral.

It is not absolutely repeatable or reproducible as is cleavage down to theoretically the very atomic layers that cause cleavage.

Parting is caused by pressures that are applied to a crystal or by twinning. The pressure breaks the crystal on a plane of weakness.

Parting

With pressure parting the actual break formed long before the crystal was excavated from the ground and may be due to tectonic or isostatic pressures that have been forced on the crystal.

Most parting is seen as fracture lines that are incomplete or healed (the crystal continued to grow and sealed the break) and might appear as striations or planes of concentrated inclusions.