Oxides and hydroxides: Pyrolusite

Diagnostic card.

MnO ₂ (manganese oxide)
Tsingonia tetragonal
Hardness 6-6,5
Specific weight 4.7-5.1
Cleavage is absent
Cracked shell
Color: dark gray, black
Color in powder black
Glitter semimetallic

It is a black powdery mineral. It is most often associated with other minerals of manganese, mostly non-crystalline. Such an association was called Vad. You can find pyrolusite in the form of earthy masses, fibrous aggregates, concretion bonds. Very rarely it is a prismatic black crystal; In this case it is called polyanite.

Name from the Greek, pyre - fire and ioysis - washing. Together with psilomelanom pyrolusite - the main manganese ore. Used for the production of chlorine, in the glass business (for discoloration) and smelting of special grades of steels.

Rarely found in the form of idiomorphic crystals - a variety of polyanite (hardness 6.5, metallic shine), pseudomorphic manganite. Pyrolusite forms radiant-crystalline masses, solid or earthy-friable; Marked as graphite. Cleavage in two directions; Density about 5; Hardness is difficult to determine, crumbles easily; Color is gray to black.

Chemical composition. Manganese (Mn) 63.2%, oxygen (O) 36.8%. Form of crystalline precipitates. Crystals are rare, only in voids can be found needle or columnar forms; For the most part, the mineral forms dense, thin (crypto) crystalline, earthy (loose) masses. Crystal structure. Lattice lattice type rutile. Class of symmetry. Ditetragonal-bipyramidal - 4 / mmm. Aggregates. Dense, reniform and stalactite-like formations, nodules, radiant and fibrous intergrowths.

Diagnostic signs.
The earthy variety gives a very characteristic feature of black color. When heated, the mineral becomes solid.

Origin.
Has a sedimentary genesis. Formed as a chemical sediment in ancient lakes, marshes, lagoons under conditions of weak water circulation, but with a high oxygen content. It can also exist as a secondary mineral formed during the oxidation of manganese minerals.

Deposits and applications.
Large deposits of dense vada and pyrolusite were found in Georgia, the Dekan (India), the state of Minas Gerais (Brazil) and South Africa. Pyrolusite is an important ore for manganese.

Pyrolusite and its varieties (psilomelan, vad, etc.) are very similar in composition, but have different appearance and properties. They were formed in the weathering zone ("iron hat") from manganese-bearing vein minerals - rhodonite, rhodochrosite, siderite, dolomite and others, (Westphalia, Thuringia in Germany). Typically, the sedimentary origin of the most known deposits of manganese ore: Nikopol (Ukraine) and Chiatura (Georgia). Sometimes the mineral was formed as a result of leaching and oxidation.

ADR 5.1
Substances that are oxidized
Risk of violent reaction, ignition or explosion if exposed to flammable or flammable substances
Do not allow the formation of a mixture of cargo with flammable or combustible substances (eg sawdust)
Yellow diamond, ADR number, black flame above the circle

ADR 4.2
Substances that are capable of self-ignition
Risk of fire due to autoignition in the event that the packaging is damaged or the source of the contents has occurred.
Can react violently with water
White upper half of diamond, red - lower, equal, ADR number, black flame

ADR 4.1
Highly flammable solids , self-reactive substances and solid desensitized explosives
Risk of fire. Flammable or combustible substances can ignite from sparks or flames. May contain self-reactive substances capable of exothermic decomposition in the case of heating, contact with other substances (such as: acids, heavy metal compounds or amines), friction or impact.
This can lead to the emission of harmful or flammable gases or vapor or spontaneous combustion. Containers can explode when heated (over-dangerous - practically do not burn).
Risk of explosion of desensitized explosives after loss of desensitizer
Seven vertical red stripes on a white background, equal in number, ADR number, black flame

ADR 8
Corrosive (corrosive) substances
Risk of burns from skin corrosion. They can react violently with each other (components), with water and other substances. The substance that spilled / crumbled can emit a corrosive vapor.
Dangerous to aquatic environment or sewer system
White upper half of diamond, black - lower, equal, ADR number, test tubes, hands

ADR 9
Other dangerous substances and articles
Risk of burns. Risk of fire. Risk of explosion.
Dangerous to aquatic environment or sewer system
Seven vertical black stripes on white background - top, white - lower half of diamond, ADR number

ADR 4.3
Substances that emit flammable gases in contact with water
Risk of fire and explosion if exposed to water.
The cargo, which crumbled, must be covered and kept dry
Blue and blue diamond, ADR number, black or white flame

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Poisonous and radioactive dangerous stones and minerals

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^** - radioactive stones and minerals (mandatory check on the standard dosimeter + ban on open sales in case of radioactivity exceeding 24 milli / g / h + additional measures of population protection)

Catalog of minerals and semi-precious stones of the world by groups

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