Lithium Minerals


The name lithium comes from the Greek word lithos which means stone because lithium was first discovered in rocks and other two alkali metals were first discovered in plants. Lithium was first found in the mineral called petalite (LiAl(Si2O5)2, lithium aluminum silicate). This mineral was first found by Brazilian scientist Jose Bonifacio in 1800.Lithium is the lightest metal and is in a group of elements called group 1 elements. It is reacts readily with oxygen and water hence it is stored in oil.

There are many types of lithium minerals of which several are of commercial importance, they are
1. Lepidolite
2. Petalite
3. Spodumene
4. Amblygonite

1. Lepidolite

Lepidolite is a lithium mica having a complex chemical composition KliAl (OH,F)2Al(SiO4)3, or K2Li4Al2F4Si8O22 which carries 2 to 4 percent of Lithia. Lepidolite is an ore of lithium and forms in granitic masses that contain a substantial amount of lithium. Lepidolite is an ore of lithium and forms in granitic masses that contain a substantial amount of lithium. Lepidolite, like other micas, has a layered structure of lithium aluminum silicate sheets weakly bonded together by layers of potassium ions.

Physical Properties
  1. Color is violet to pale pink or white and rarely gray or yellow.
  2. Luster is vitreous to pearly.
  3. Transparency crystals are transparent to translucent.
  4. Crystal System is monoclinic; 2/m
  5. Hardness is 2.5.
  6. Specific Gravity is approximately 2.8Streak is white.
  7. Cleavage is perfect in one direction producing thin sheets or flakes.
  8. Fracture is not readily observed due to cleavage but is uneven.
Applications

· Lepidolite is a lithium ore and it is used in making ornamental stones.
· It is also used as an heat insulator in industries.


2. Petalite

Petalite is also known as castorite. It crystallises in mono clinic system. Petalite can be converted into spodumene and silica by roasting method.

Physical properties

· The color of petalite is from colorless to gray, yellow and white.
· Crystal habit is tabular prismatic crystals and columnar masses.
· Crystal system is monoclinic 2/m.
· Cleavage is perfect in one plane.
· Specific gravity is 2.42.
· Specific gravity is about.
· Luster is vitrous to pearly.
· Streak is colourless.
· Hardness ranges between 6 and 6.5.


3.Spodumene
Spodumene is a rock forming mineral in granites and pegmatites that bear other lithium minerals. Spodumene has 2 types called Kunzite and Hiddenite. Kunzite is more commonly known type and is known by most gemstone collectors and fanciers. It is a lovely pink to lilac color that is unique in the gem kingdom. Where as hiddenite is not available that abundantly. It has an usual green color that is unlike either peridot or emerald.

Physical properties
· Color is white, colorless, gray, pink, lilac, and green.
  • Crystal System is monoclinic; 2/m
  • Crystal Habits include prismatic, generally flattened and elongated crystals. The termination is usually the two faces of a dome or rounded, curved and faces indisernable. Crystal faces are often pitted and rough.
  • Luster is vitreous.
  • Streak is white.
  • Transparency crystals are transparent to translucent.
  • Cleavage is perfect in two direction at close to right angles and a parting direction that breaks diagonally transect one of the cleavage angles and is parallel to the typical flattening of the crystals.
  • Fracture is splintery due to the cleavage and parting.
  • Hardness is 6.5 – 7.
  • Specific Gravity is approximately 3.2.
4. Amblygonite
Amblygonite's name comes from the Greek words for blunt angles in allusion to its variously angled cleavages. Amblygonite has a fairly compact structure having chemical formula (Li, Na)AlPO4(F, OH), Lithium Sodium Aluminum Phosphate Fluoride Hydroxide. Amblygonite is similar to rocks such as such as quartz and albite. The general appearance of amblygonite does resemble these two minerals especially the albite but it can be differentiated with a flame test for lithium, density and by its unusual cleavage. Since amblygonite has lithium in its formula, it gives a reliable lithium result with a flame test. Powdered amblygonite which is placed in a gas flame will produce a brightly colored red flame. This is evidence for the presence of lithium.

Physical properties
  • Color is generally white or creamy, but can also be colorless or pale yellow, green, blue, beige, gray or pink.
  • Luster is vitreous to greasy and pearly on cleavage surfaces.
  • Transparency: Specimens are translucent to less commonly transparent.
  • Crystal System is triclinic, bar 1.
  • Crystal Habits include short prismatic, tabular or equant crystals referred to as lath-shaped, but more commonly found as anhedral masses and compact grains. Twinning forms elongated, flatten crystals. Lamellar twinning is sometimes seen.
  • Cleavage is in four directions all with varying quality with one direction being perfect, two directions being good and one direction being only distinct. All cleavage angles are non-right angles.
  • Fracture is uneven to conchoidal.
  • Hardness is 5.5 - 6
  • Specific Gravity is approximately 2.98 - 3.11.
  • Streak is white.

Applications/ Uses of Lithium Minerals
  • Lithium chloride is largely used in refrigeration and air-conditioning plants as it is one of the most hygroscopic of all inorganic salts. Lithium hydroxide is used for absorbing carbon dioxide in submarines and as a constituent of respirators. Chloride and fluoride compounds are used in welding and brazing.
  • Lithium is also used as a scavenging material for metallic minerals and gases in the metallurgy of several metals.
  • Lithium minerals are used in glass and ceramic industries for their lithia content. Lepidolite, spodumene and amblygonite are used along with glass sand-batch for the manufacture of lithium glass. It has the lowest melting point and lowest annealing temperature of all alkali glasses. Lithium reduces its co-efficient of expansion.
  • Some lithium compounds are considered to use as rocket propellants and in nuclear reactors. Lithium has two stable isotopes with mass numbers of 6 and 7 with relative abundance of 7.5 and 92.5%. The former isotope is used for the production of tritium, extra heavy hydrogen, an intermediate explosive in the manufacture of hydrogen bombs.
Question and Answers
1.Mention the types of lithium minerals?Ans. There are mainly 5 types of lithium minerals a) Lepidolite b) Petalite c) Spodumene d) Amblygonite
2. what is the chemical composition of lepidolite?
Ans. KliAl (OH,F)2Al(SiO4)3, or K2Li4Al2F4Si8O22.

3. Mention the physical propertyies of Spodumene?
Ans.
· Color is white, colorless, gray, pink, lilac, and green.
· Crystal System is monoclinic; 2/m.
· Luster is vitreous.
· Transparency crystals are transparent to translucent.
· Hardness is 6.5 – 7.
· Specific Gravity is approximately 3.2.

4. What are the applications of lithium mineral?
Ans.
· Lithium is also used as a scavenging material for metallic minerals and gases in the metallurgy of several metals.
· Lithium minerals are used in glass and ceramic industries for their lithia content. Lepidolite, spodumene and amblygonite are used along with glass sand-batch for the manufacture of lithium glass. It has the lowest melting point and lowest annealing temperature of all alkali glasses. Lithium reduces its co-efficient of expansion.

References: www.wikipedia.com www.galleries.com

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