Platinum (Pt) is a rare and highly valuable transition metal found in approximately 25 % of consumer goods. This fact sheet outlines its chemical, physical, mechanical, and thermal properties and explores its classification as a precious metal.
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Platinum: Properties
| Category | Property | Value |
|---|---|---|
| General Properties | ||
| Atomic Number | 78 | |
| Atomic Weight | 195.084 | |
| Color | Steel grey to silvery-white | |
| Physical Properties | ||
| Density | 21.45 g/cm³ (0.7749 lb/in³) | |
| Melting Point | 1768.3°C (3214.9°F) | |
| Boiling Point | 3825°C (6917°F) | |
| Crystal Structure | Face-centered cubic | |
| Corrosion Resistance | Highly resistant to corrosion and chemical attack | |
| Chemical Properties | ||
| Oxidation States | +2, +4 (most common); +1, +3, +5, +6 (less common) | |
| Electronegativity | 2.2 | |
| Electrode Potential | 1.2 V | |
| Ionic Radius | 0.650 Å | |
| X-ray Absorption Edge | 1.6524 Å | |
| Electrochemical Equivalent | 1.816 g/Ah | |
| Thermal Neutron Cross Section | 9 barns/atom | |
| Mechanical Properties | ||
| Tensile Strength | 125-165 MPa (18100-23900 psi) | |
| Young’s Modulus | 168 GPa (24800 ksi) | |
| Bulk Modulus | 230 GPa (33359 ksi) | |
| Shear Modulus | 62 GPa (8990 ksi) | |
| Poisson’s Ratio | 0.39 | |
| Elongation at Break | 35% | |
| Brinell Hardness | 300-500 MPa | |
| Vickers Hardness | 400-550 MPa | |
| Thermal Properties | ||
| Thermal Conductivity | 69.1 W/m·K (480 BTU in/hr.ft².°F) | |
| Thermal Expansion Coefficient (@20°C) | 9.10 µm/m°C (5.06 µin/in°F) | |
| Specific Heat Capacity | 133 J/(kg·K) | |
Why Is Platinum Considered a Precious Metal?
Platinum remains one of the rarest and most valuable precious metals. Unlike gold and silver, platinum has limited above-ground reserves, meaning most of the metal in circulation comes from mining.
The global supply of platinum is primarily dominated by South Africa, which accounts for about 70-75 % of production. Russia, Zimbabwe, and North America also contribute significantly.
The extraction of platinum is a challenging and resource-intensive process. Current data indicates that platinum ore typically contains between 3 and 6 grams of platinum per tonne of ore. This translates to approximately 10 to 40 tonnes of ore being required to produce just one ounce (31.1035 grams) of platinum.
The ore extraction process involves drilling, blasting, and mechanical transportation to the surface. Once extracted, the ore undergoes complex refining processes to separate the platinum group metals (PGMs) from other minerals. These processes include froth flotation, smelting, chemical leaching, and precipitation.
The process is time-consuming, often taking up to six months to process a batch of ore. Every year, around 190 tons of platinum are mined, compared to approximately 3,300 metric tons of gold. This significant difference in production volumes contributes to platinum’s status as a precious metal.
Platinum Jewelry: Is Platinum Better than Gold?
Platinum’s unique physical and chemical properties make it a superior choice for certain jewelry applications, particularly those that prioritize durability and purity.
Unlike gold, which is often alloyed with other metals to improve its strength, platinum used in jewelry is typically 90-95 % pure. This high purity not only enhances its hypoallergenic properties but also ensures that platinum retains its weight and value over time.
The production of platinum jewelry involves complex processes due to the metal’s high melting point (1768.3°C) and density (21.45 g/cm³). Traditional casting methods require specialized equipment capable of handling extreme temperatures, as well as investment materials resistant to platinum’s reactivity at such conditions.
For intricate designs, modern techniques like selective laser melting (SLM) are increasingly being used. SLM allows for precise 3D printing of platinum alloys, overcoming challenges associated with traditional casting, such as defects caused by mold reactivity and shrinkage.
Platinum’s durability is another key advantage. Its high density makes it resistant to deformation and wear, ensuring that gemstone settings remain secure over decades of use. This is particularly important in “invisible settings,” where stones are held without visible prongs or supports, relying solely on the strength of the metal.
Platinum is significantly heavier than gold (about 60 % denser). This gives platinum jewelry a substantial feel. While this adds to its appeal, it also makes platinum more expensive to work with, both in terms of material cost and production processes.
Whether platinum is “better” than gold depends on personal preference and priorities. Platinum’s durability and unique appearance make it an excellent choice for those seeking heirloom-quality jewelry designed to last a lifetime.