Glory and Hellene in the Field

Glory and Hellene

Conditions necessary for the formation of hydrothermal mineral deposits

Conditions necessary for the formation of hydrothermal mineral deposits include:
(1) Presence of hot water to dissolve and transport minerals,
(2) Presence of interconnected openings in the rock to allow the solutions to move,
(3) Availability of sites for the deposits, and
(4) Chemical reaction that will result in deposition.

What are the five most common rock-forming mineral groups?

What are the five most common rock-forming mineral groups?
1. Silicates
2. Oxides
3. Sulphides
4. Carbonates
5. Sulphate
6. Halides
7. Phosphates e.t.c

What factors controls the shape of a well formed crystal?

The following are major factors that influence the shape of a well formed crystal:
 

•   Symmetry properties of the underlying lattice
•  Rates of growth; - the overall shape of the crystal is determined by the relative rates of growth of the various faces. Thus the slower the growth rate, the larger the face. 
• The conditions under which a crystal is grown can affect its habit. The Temperature, degree of super-saturation, nature of the solvent all have their effects, and these may affect the growth of different faces in different ways. 
• The presence of impurities in the solution can radically alter the habit of a crystal, as seen in the following table for the growth of sodium chloride: 

no impurity           Fe(CN)64–         formamide Pb2+,             Cd2+          polyvinyl alcohol
cubes                     dendrites                octahedra              large crystals          needles

These effects presumably come about because these substances preferentially adsorb to certain faces, impeding their growth.

List down at least five examples of sulphide minerals.

List down at least five examples of sulphide minerals.
Sulfide ores/minerals
i. argentite (silver sulfide),
ii. cinnabar (mercury),
iii. galena (lead sulfide),
iv. molybdenite (molybdenum sulfide),
v. pentlandite (nickelsulfide]),
vi. realgar (arsenic sulfide),
vii. stibnite (antimony),
viii. sphalerite (zinc sulfide),
ix. pyrite (iron disulfide), and
x. chalcopyrite (iron-copper sulfide).