Natural platinum is often containediron、iridium、palladium、rhodiumEquiimpurityPlatinum mineral。The color is silver white to dark steel gray, belonging to equiaxed crystal system.Crystals are rare.It usually forms an irregular granular or scaly aggregate.No cleavage, serrated fracture, bright stripe, light steel gray.density15~19，hardness4~4.5。It is rich in ductility and can be divided into primary ore and ore sand.It can be used to extract platinum, iridium, palladium, rhodium, etc.
Natural platinum mainly occurs in basic and ultrabasic igneous rocks, especiallyDunite(Dunite).
PlatinumSiderophile elementIt also has obvious sulfur affinity.In addition to forming the simple mineral "natural platinum", platinum often forms metal compounds with other platinum group elements such as iron, nickel, copper, silver, gold, etc., and forms simple or complex compounds with sulfur, selenium, tellurium, arsenic, antimony, bismuth, etc. with strong non-metallic properties, or even with tin, lead, indium, etc.Therefore, there are many minerals involved in platinum in nature.Natural platinum is crystallized into equiaxed crystal system, withMetallic luster。With the increase of iron content, the color changes from silver white to steel gray, and the striation is bright and steel gray.When rich in ironmagnetic。As the melting point of natural platinum is up to 1769 ℃, it has excellent ductility and ductility, good conductivity and stable chemical properties.Therefore, in addition to making jewelry, it is also widely used in industrial materials.The natural platinum composition often contains iron impurities, and the color will be black.When it reaches 9% to 11%, it is called coarse platinum ore, and when it is higher, it is called coarse platinum oreIron platinum ore, up to 28 percent.In fact, the so-called natural platinum is mostly crude platinum ore.It also often contains palladium, iridium, rhodium, etc.
structure
Natural platinum isHexaoctahedral crystal class, granular orGrapeShape, occasionally cubic crystal.The density is 15 g/cm3~19 g/cm3.Hardness is 4Mohs hardness~4.5 Mohs hardness.Mainly platinum (Pt)Natural element minerals。Metallic platinumMain mineralsRaw materials, crystals into cubes.However, it is quite rare. It is mainly produced in granular or scaly aggregates in nature, and a few are aggregated into irregular large nuggets.The color is tin white to iron gray, so it is also called“platinum”。It is greatly different from natural silver in terms of high specific gravity and hardness.
chemical property
Platinum has stable chemical properties;It does not react with hydrochloric acid, nitric acid, sulfuric acid and organic acid at normal temperature. It is called "the most corrosion-resistant metal", but it is soluble in aqua regia.Platinum has excellent oxidation resistance, good catalysis and thermoelectricity.Platinum can be stretched into a thin wire with a diameter of 0.001 mm and hammered into foil with a thickness of 0.127 microns. Even if a gram of platinum is pulled into a thin wire with a length of 1.6 kilometers, it will not break.
Natural platinum is mainly produced in olivesgabbro（Olivinegabbro）、Pyroxenite（Pyroxenite）、Peridotite(Peridotite) and dunite.Paragenetic mineralyesolivine、Chromite（Chromite）、pyroxeneAnd magnetite, etc.In the vicinity of igneous rocks containing native platinum, platinum bearing residual deposits or placer deposits are often formed.Its chemical properties are extremely inactive.It is produced in natural metal state in nature, and its acid and alkali resistance is particularly strong.It is insoluble in any acid except hot aqua regia.
characteristic parameter
Crystal system and space group: equiaxed crystal system, Fm3m.
Cell parameter: a0=3.924Å
Chemical composition: mainly platinum, but often contains a small amount of other elements, such as Fe, Ni, Pd, Au, Cu and other mixed substances.
Color: depending on the iron content, from silver white to steel gray.
Others: ductile, melting point 1774 ℃.When iron is contained, it is slightly magnetic and is a good conductor of electricity and heat.
Reflectivity: 70% for green light and red light, 73% for orange light.
Main purpose
Natural platinum is the main source of platinum.Platinum is a precious metal, which is often used to make jewelry, such as rings, bracelets and necklaces, because of its beautiful color, strong ductility and expansibility.Due to the heightchemical stabilityIt is naturally used to make advanced chemical utensils (crucibles in laboratories) or special alloys with nickel, and is used in electric power industry and contact reaction converters for automobiles.
PlatinumOfantioxidantStrong force,melting pointHigh, so it is also used for makingSpace suit。During the World War II, platinum had a very important military use because it was a goodcatalyzer, high melting point.The US government once banned platinum for non military purposes.No one's skin will be allergic to platinum, which can be made ofelectrodebe used forElectronic pulseRegulator, directly inserted into human heart, for treatmentArrhythmiapatient.
Platinum can also be used to makeWaterproof watch。As a catalyst, platinum is widely used in automobile exhaust purification devices, playing an important role in protecting the environment.[1]
Through the preliminary study on the metallogenic geological characteristics of natural platinum deposits, the following knowledge of ore source exploration can be obtained:
1. Layered basicity of earlier magnetite bearing bedsUltrabasic rockIt is the initial ore source bed of the natural platinum deposit. The obvious magnetic anomaly can reflect the occurrence and scale of the rock body and the existence of the internal magnetic ore bed.
2. The later tectono hydrothermal alteration plays an important role in the migration, enrichment and mineralization of natural platinum.
3. The mineralized rocks have obvious sub amphibolization, chloritization, nazoisitization, pyritization, and obvious limonitization and malachitization on the surface, which are important prospecting indicators.[2]
