Zirconium is a transition metal that was discovered in 1789 within the mineral zircon. It has several stable and one radioactive isotope. While difficult to isolate pure zirconium due to its chemical similarity to hafnium, the Kroll process is commonly used. Zirconium has many applications including use in nuclear reactors due to its resistance to neutron absorption, as an alloy for steel, and in gemstones like cubic zirconia.

2.  Atomic Number: 40
 Symbol: Zr
 Group: 4B (Transition Metal)
 Atomic Weight: 91.224
 Electron Configuration: [Kr] 4d2 5s2
 Specific Heat: 0.281 J/g°C

3.  Melting Point: 1852.0 °C
 Boiling Point: 4377.0 °C
 Density: 6.506 g/cm3
 State at Room Temp: Solid
 Color: Grayish-white

4.  Martin Heinrich Klaproth, a leading German
chemist in his time, discovered zirconium as
part of the compound zircon in 1789. Zircon’s
chemical name is zirconium silicate and its
formula is ZrSiO4.
 Zirconium was named from the Persian word
“zargun” meaning “gold-like.” This name was
not a reference to its chemical properties, but
rather to the gold color of the mineral zircon.

5. Some photos of the gold-colored mineral zircon, ZrSiO4

6.  Although recognized as an element in
1789, zirconium was not isolated until 1824 by
a Swedish chemist named Jöns Jacob Berzelius.
 He isolated the element by heating a mixture of
potassium and potassium zirconium fluoride in
an iron tube. The reaction produced a black
powder that was 93% zirconium.

7.  Zirconium has 28 known isotopes, 5 of which
are naturally occurring. 4 of those isotopes are
stable, and the other is radioactive. The
naturally occurring isotopes and their
abundances are listed below:
90Zr: Stable, 51.45%
91Zr: Stable, 11.22%
92Zr: Stable, 17.15%
94Zr: Stable, 17.38%
96Zr: Radioactive, 2.80%
(Half-life 3.8 X 1019 years)

8.  Zirconium is most easily found in mineral
deposits of zircon (previously mentioned) and
in zirconium dioxide, ZrO2 , which is most
often associated with lunar rocks.
 Obtaining pure zirconium is very difficult
because it is chemically similar to hafnium, an
element of the same group which is always
found mixed with deposits of zirconium.
 Commercial-grade zirconium can contain
anywhere from 1 – 3% hafnium.

9.  The Kroll method is used to purify ZrO2 into
zirconium. The reactions involved include the
following:
ZrO2 + 2Cl2 + 2C (900°C)  ZrCl4 + 2CO
ZrCl4 + 2Mg (1100°C)  2MgCl2 + Zr
Air is excluded from these reactions so as to
avoid contamination of the product with
oxygen or nitrogen.

10.  Zirconium is resistant to corrosion by acids and
bases, as well as salt water and various other
agents. For that reason, it is used in high
performance pumps and valves.
 Since it does not easily absorb
neutrons, zirconium is widely used in nuclear
reactors. The zirconium used for this purpose must
be nearly free of hafnium, as hafnium can absorb
neutrons.
 Zirconium is also used as an alloying agent in
steel, to make surgical equipment, and as a
“getter” or a material that combines with and
removes trace gases from vacuum tubes.

11.  The majority of zirconium compounds are used to
make gems in jewelry.
 Colorless specimens of zircon (ZrSiO4) are often
used as inexpensive replacements for diamonds.
These are known as “Matura Diamonds.”
 Cubic zirconia (a form of is also a popular
synthetic gem. It can be colorless, but is easily
dyed almost any color. Many inexpensive
“birthstone” or engagement rings involve the use
of cubic zirconia.

12.  Zirconium dioxide (ZrO2) can withstand very high
temperatures and is used to make crucibles and to
line the walls of high temperature furnaces
 Zirconium carbonate (3ZrO2·CO2·H2O) is used in
lotions to treat poison ivy.
 Many different Zirconium compounds are used to
make paints, pigments, paper, and adhesives.

13.  Cubic zirconia is judged on a standard of cut
and clarity, as are diamonds. At one time, the
gems were though to have been “soft
diamonds.”
 When finely divided, the metal may ignite
spontaneously in air, especially at elevated
temperatures.
 Zirconium of about 99.6% purity is available at
a cost of about $150/kg.

16.  http://chemistry.about.com/od/elementfacts
/a/zirconium.htm
 http://www.facts-about.org.uk/science-
element-zirconium.htm
 http://www.chemicool.com/elements/zirconi
um.html