Cobalt
Cobalt is a hard, silvery-blue metal long associated with vivid blue pigments, though today it's just as well known for powering rechargeable batteries. Its name has an unusually colorful backstory, rooted in the frustration of miners who blamed troublesome ore on mischievous underground spirits.
- Group · Period
- 9 · 4
- At room temp
- solid
- Melts at
- 1768 K
- Density
- 8.86 g/cm³
- Discovered
- 1735
Uses
Cobalt’s biggest modern use is in rechargeable batteries, where cobalt compounds in the cathode help lithium-ion batteries store more energy and last longer — a major reason it’s closely tied to the electric vehicle and consumer electronics industries. It’s also a key ingredient in superalloys used in jet engine turbine blades, which need to keep their strength at extremely high temperatures. Cobalt compounds continue to be used as vivid blue pigments in glass, ceramics, and paint, a use that dates back thousands of years.
Cobalt is also naturally ferromagnetic, and alloys containing it are used in magnets and certain data storage materials.
History
Cobalt-containing minerals were used to color glass and pottery deep blue as far back as ancient Egypt and China, but for centuries the ore itself frustrated miners: it resembled valuable metal ore but produced none when smelted, and instead released toxic fumes. German miners blamed a mischievous spirit called a “kobold” for the trouble, and the name stuck. Swedish chemist Georg Brandt isolated the metal itself around 1735, demonstrating that the color in these minerals came from a genuinely new element rather than from bismuth or arsenic as some had assumed, and he named it cobalt after the old miners’ legend.
Fun facts
- Cobalt compounds have been used to color glass and ceramics a deep blue for thousands of years, long before cobalt was recognized as an element.
- It's named after 'kobold,' a mischievous spirit from German mining folklore that miners blamed for ore that looked promising but yielded no useful metal.
- Cobalt is a key ingredient in the cathodes of many lithium-ion batteries, making it an important material for electric vehicles and portable electronics.
Frequently asked questions
Is cobalt magnetic?
Yes — cobalt is one of only a few elements that's naturally ferromagnetic at room temperature, alongside iron and nickel. It's used in various magnetic alloys and recording materials precisely because of this property, in addition to its more famous battery and pigment uses.
Why is cobalt used in electric vehicle batteries?
Cobalt helps stabilize the structure of the cathode material in many lithium-ion batteries, improving their energy density and lifespan. Because cobalt is relatively scarce and its mining raises ethical and supply concerns, battery makers have been working to reduce how much of it their designs require, but it remains an important component in many current battery chemistries.
Why is cobalt blue such a distinctive color?
When cobalt is incorporated into glass or ceramic glazes, it produces an intense, stable blue that doesn't fade the way some organic dyes do. Artisans in ancient Egypt and China discovered this effect using cobalt-containing minerals centuries before anyone understood cobalt as a chemical element, and the color remains popular today.
Compounds
4 notable compounds containing Co
- CoAl2O4industrial
Cobalt blue
A vividly blue spinel-structured pigment formed by firing cobalt(II) and aluminum oxides together. It has been prized for centuries for its rich, stable color in art and ceramics.
Used for: Blue pigment in paints, ceramics, and glass
- Co3O4oxide
Cobalt(II,III) oxide
A black spinel-structured oxide that combines cobalt in both the +2 and +3 oxidation states within one crystal lattice, giving it useful magnetic and catalytic behavior.
Used for: Ceramic pigment and electrode material studied for lithium-ion batteries
- CoCl2salt
Cobalt(II) chloride
A salt famous for its reversible color change with humidity — deep blue when anhydrous and pink when hydrated — which makes it a classic visual indicator of moisture in the air.
Used for: Humidity indicator in silica gel packets and desiccants
- CoSO4salt
Cobalt(II) sulfate
A reddish crystalline salt (in its common hydrated form) that provides a water-soluble source of cobalt ions for industrial and agricultural applications.
Used for: Electroplating baths and trace-mineral additive in animal feed
Isotopes
30 known isotopes
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| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Co-59 stable | 100% | Stable | — | -62,229.84 keV | 8,768.04 keV | — |
Show all 30 isotopes
| Co-48 | — | — | Proton emission | 1,730 keV | 7,595 keV | — |
| Co-50 | — | 38.8 ms | Electron capture / beta-plus decay (100%), ECP (70.5%), EC2P | -17,589.4 keV | 8,000.64 keV | 1.18 × 10-14 eV |
| Co-51 | — | 68.8 ms | Electron capture / beta-plus decay (100%), ECP (3.8%) | -27,342.15 keV | 8,193.25 keV | 6.63 × 10-15 eV |
| Co-52 | — | 104 ms | Electron capture / beta-plus decay (100%), Beta-plus, proton emission | -34,343.98 keV | 8,325.56 keV | 4.39 × 10-15 eV |
| Co-53 | — | 240 ms | Electron capture / beta-plus decay (100%) | -42,659.38 keV | 8,477.66 keV | 1.90 × 10-15 eV |
| Co-54 | — | 193.28 ms | Electron capture / beta-plus decay (100%) | -48,010.07 keV | 8,569.22 keV | 2.36 × 10-15 eV |
| Co-55 | — | 17.53 h | Electron capture / beta-plus decay (100%) | -54,030 keV | 8,669.62 keV | 7.23 × 10-21 eV |
| Co-56 | — | 77.236 d | Electron capture / beta-plus decay (100%) | -56,040.52 keV | 8,694.84 keV | 6.84 × 10-23 eV |
| Co-57 | — | 271.74 d | Electron capture (100%) | -59,345.66 keV | 8,741.88 keV | 1.94 × 10-23 eV |
| Co-58 | — | 70.86 d | Electron capture / beta-plus decay (100%) | -59,847.29 keV | 8,738.97 keV | 7.45 × 10-23 eV |
| Co-60 | — | 1925.28 d | Beta-minus decay (100%) | -61,650.44 keV | 8,746.77 keV | 2.74 × 10-24 eV |
| Co-61 | — | 1.649 h | Beta-minus decay (100%) | -62,898.18 keV | 8,756.15 keV | 7.69 × 10-20 eV |
| Co-62 | — | 1.54 m | Beta-minus decay (100%) | -61,424.4 keV | 8,721.33 keV | 4.94 × 10-18 eV |
| Co-63 | — | 27.4 s | Beta-minus decay (100%) | -61,851.55 keV | 8,717.8 keV | 1.67 × 10-17 eV |
| Co-64 | — | 0.30 s | Beta-minus decay (100%) | -59,792.44 keV | 8,675.52 keV | 1.52 × 10-15 eV |
| Co-65 | — | 1.16 s | Beta-minus decay (100%) | -59,185.21 keV | 8,656.88 keV | 3.93 × 10-16 eV |
| Co-66 | — | 0.20 s | Beta-minus decay (100%) | -56,408.54 keV | 8,605.94 keV | 2.28 × 10-15 eV |
| Co-67 | — | 0.425 s | Beta-minus decay (100%) | -55,321.78 keV | 8,581.74 keV | 1.07 × 10-15 eV |
| Co-68 | — | 0.20 s | Beta-minus decay (100%) | -51,642.59 keV | 8,520.13 keV | 2.28 × 10-15 eV |
| Co-69 | — | 227 ms | Beta-minus decay (100%) | -50,385.45 keV | 8,495.41 keV | 2.01 × 10-15 eV |
| Co-70 | — | 112 ms | Beta-minus decay (100%), Beta-minus, neutron emission | -46,524.96 keV | 8,434.2 keV | 4.07 × 10-15 eV |
| Co-71 | — | 80 ms | Beta-minus decay (100%), Beta-minus, neutron emission (16%) | -44,369.93 keV | 8,398.73 keV | 5.70 × 10-15 eV |
| Co-72 | — | 59.9 ms | Beta-minus decay (100%), Beta-minus, neutron emission (6%) | -40,300 keV | 8,338 keV | 7.62 × 10-15 eV |
| Co-73 | — | 40.7 ms | Beta-minus decay (100%), Beta-minus, neutron emission (22%), B-2N | -37,970 keV | 8,302 keV | 1.12 × 10-14 eV |
| Co-74 | — | 31.3 ms | Beta-minus decay (100%), Beta-minus, neutron emission (18%), B-2N | -33,540 keV | 8,239 keV | 1.46 × 10-14 eV |
| Co-75 | — | 30 ms | Beta-minus decay (100%), Beta-minus, neutron emission (16%), B-2N | -30,560 keV | 8,197 keV | 1.52 × 10-14 eV |
| Co-76 | — | 21.7 ms | Beta-minus decay (100%), B-2N, Beta-minus, neutron emission | -25,660 keV | 8,131 keV | 2.10 × 10-14 eV |
| Co-77 | — | 13.0 ms | Beta-minus decay (100%), Beta-minus, neutron emission, B-2N | -21,910 keV | 8,082 keV | 3.51 × 10-14 eV |
| Co-78 | — | — | Beta-minus decay (100%), B-4N, B-3N | -15,320 keV | 7,997 keV | — |