mineralogy flashcards
What is Mineralogy?
The study of naturally occurring crystalline substances (minerals).
Define a crystal.
A homogenous solid possessing long-range, three-dimensional internal orders.
What are the five key characteristics of a mineral?
- Naturally occurring – Formed by natural processes.
- Homogenous solid – Cannot be physically subdivided into simpler compounds.
- Definite chemical composition – Atoms occur in specific but not always fixed ratios.
- Ordered atomic arrangement – Crystalline structure with a repeating pattern.
- Formed by inorganic processes – Not biologically produced.
Who initiated the immersion method in 1815?
Cordier, a French naturalist. A mineral, Cordierite, was named after him.
What did William Nicol invent in 1828?
The polarizing device, which allowed the study of light behavior in crystalline substances, leading to the polarizing microscope.
What was the significance of X-ray crystallography in the late 19th century?
Federov, Schoenflies, and Barlov developed theories on internal symmetry and crystal order, forming the foundation for X-ray crystallography.
Who demonstrated that crystals diffract X-rays in 1912?
Max Von Laue suggested the experiment, conducted by Friedrich and Knipping. X-ray diffraction became a key method in mineral study.
What did W.H. and W.L. Bragg publish in 1913?
The earliest crystal structure determinations, leading to Bragg’s Law in X-ray diffraction.
What technological advancement in 1960 helped in mineral chemistry studies?
The electron microprobe, which allowed detailed chemical analysis of minerals and synthetic compounds.
What is Steno’s Law?
The Law of Constancy of Interfacial Angles states that angles between similar crystal faces remain constant regardless of crystal size or shape.
Name the six crystal systems.
- Isometric (Cubic) Three equal-length axes intersect at 90�.
- Tetragonal – Three axes at 90°, but one is a different length.
- Orthorhombic – Three unequal-length axes, all at 90°.
- Hexagonal – Four axes, three at 120°, one perpendicular.
- Monoclinic – Three unequal-length axes, two intersect obliquely, one at 90°.
- Triclinic – Three unequal-length axes, all intersect at angles other than 90°.
What is the difference between a crystalline and amorphous solid?
Crystalline solid Ordered atomic structure (e.g., quartz).
Amorphous solid – Random atomic structure (e.g., glass).
Why is synthetic ruby not considered a mineral?
It is not naturally occurring.
How does a mineral differ from a rock?
Mineral – A single, naturally occurring crystalline substance.
Rock – An aggregate of minerals (monomineralic or polymineralic).
What is a polymorph?
A mineral with the same chemical composition but different crystal structures (e.g., graphite and diamond).
What is a mineraloid?
A substance that lacks a crystalline structure, such as opal or obsidian.
What are ore minerals?
Minerals from which one or more metals can be extracted profitably (e.g., hematite for iron, galena for lead).
What are industrial minerals?
Minerals used in industry, such as Quartz (glassmaking), Feldspar (ceramics), and Gypsum (cement and drywall).
What qualifies a mineral as a gemstone?
It must possess beauty, durability, rarity, fashionability, and portability (e.g., diamond, ruby, sapphire).
What minerals were used in the Stone Age?
Flint for tools, red hematite, and black manganese oxides for pigments.
Who wrote the first recorded work on minerals?
Theophrastus (327-287 BC), a Greek philosopher.
What is ‘De Re Metallica,’ and why is it significant?
Written by Georgius Agricola in 1556. First detailed work on mining practices and mineralogy. Translated by U.S. President Herbert Hoover and his wife.
What was Nicholas Steno’s contribution to crystallography in 1669?
He discovered that interfacial angles remain constant between corresponding crystal faces.
What device did Carangeot invent in 1780?
The contact goniometer, used to measure interfacial angles of crystals.
What did Rome de L’Isle confirm in 1783?
Steno’s Law of Consistent Interfacial Angles.
What did Rene J. Hauy propose in 1784?
That crystals are built from tiny identical building blocks, which he called integral molecules.
What is the Theory of Rational Indices for Crystal Faces?
Proposed by Hauy in 1801, it explains why crystal faces are arranged in predictable patterns.
How did Berzelius contribute to mineralogy between 1779-1848?
He and his students classified minerals based on chemistry, forming the basis of modern mineral classification.
What did Wollaston invent in 1809?
The reflecting goniometer, which allowed for precise crystal face measurements.
