Your Cart is Empty

Polar Chemical Twins Cubes Collection: Nb & Ta, W & Mo, Zr & Hf


Elemental metallic 1 cm elemental cubes

These highly polished cubes are great educational tools


Each cube is highly polished by hand and laser engraved with its periodic info.

*Each cube comes with an InvisiDisplay™ Case.

About the collection

At Polar Metals, we seek to spice up your life with interesting and unusual metals in unexpected ways. The elements on the periodic table are everywhere, in fact, they make up everything! We are bringing you the Polar Chemical Twins Cubes Collection.

Each cube is solid and of high purity between 99.5% and 99.99%, highly polished by hand for many hours to reach a mirror finish, and laser engraved with the element's periodic info.

Here are some interesting facts about the Chemical Twins of metals. Chemical Twins are those elements in which the properties of some elements are the same. They are Nb and Ta, Zr and Hf, W and Mo, Tc and Re. This effect arises due to the lanthanide contraction.

Niobium and Tantalum

Niobium and Tantalum are transition metals almost always paired together in nature. These “twins” are difficult to separate because of their shared physical and chemical properties.
In 1973, John Winthrop found a sample in a Massachusetts mine and sent it to the British Museum in London. In 1801, English chemist Charles Hatchett found a new element in that mineral sample and named it columbium. In 1802, Swedish scientist Anders Ekberg discovered tantalum, but it was confused with niobium because of its twinned properties, until 1864, when it was recognized as a separate element. In 1949, Niobium was officially adopted as the name of the element.
Niobium is a lustrous, gray, ductile metal with a high melting point, relatively low density, and superconductor properties. Tantalum is a dark blue-gray, dense, ductile, very hard, and easily fabricated metal. It is highly conducive to heat and electricity and renowned for its resistance to acidic corrosion. These special properties determine their primary uses and make niobium and tantalum indispensable.

Tungsten and Molybdenum

Molybdenum and tungsten are considered geochemical twins because the lanthanide contraction (filling of 4f shells in W) results in similarities in their atomic/ionic radii and bond lengths.
Although differing in their outer shell electron configuration (Mo 4d5 5s1, W 4f14 5d4 6s2), the two elements are nonetheless similar in their oxidation states and coordination numbers.
During World War I and World War II, molybdenum saw strategic importance as a substitute for tungsten in high-speed steel because of its lower density and more stable price.
Both tungsten and molybdenum are refractory metals. They have an extremely high melting point (W:3422 °C, Mo 2623 °C, excellent conductivity, and corrosion resistance.

Zirconium and Hafnium

Zirconium and Hafnium are both corrosion-resistant metals that are widely used in the chemical and nuclear-reactor industries in applications for which corrosion resistance, structural stability at high temperatures, and specific alloying properties and (or) specific neutron absorption characteristics are required.
They are both refractory lithophile elements that have nearly identical charges, ionic radii, and ionic potentials. As a result, their geochemical behavior is generally similar.
Both elements are classified as incompatible because they have physical and crystal-chemical properties that exclude them from the crystal lattices of most rock-forming minerals.


  • Zirconium: 6.5g, 99.4% purity
  • Hafnium: 13.3g, 99.6% purity
  • Molybdenum: 10.2g, 99.95% purity
  • Tungsten: 19.2g, 99.95% purity
  • Niobium: 8.5g, 99.9% purity
  • Tantalum: 16.6g, 99.95% purity

So far, we have brought 29 Elements to you: Silver, Silicon, Germanium, Nickel, Chromium, Zinc, Niobium, Tantalum, Hafnium, Rhenium, Thulium, Lutetium, Scandium, Ruthenium, Platinum, Palladium, Gold, Iridium, Osmium, Titanium, Cobalt, Magnesium, Zirconium, Molybdenum, Copper, Aluminum, Carbon, Iron and Tungsten.

*Note: Please wear gloves when handling.

Customer Reviews

Be the first to write a review

Get the free gifting guide instantly: