The following was retrieved from Wikipedia, the free encyclopedia :(en.wikipedia.org/wiki/Azurite) on February 28, 2020.
"Azurite is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the type locality at Chessy-les-Mines near Lyon, France. The mineral, a carbonate with the chemical formula Cu3(CO3)2(OH)2, has been known since ancient times, and was mentioned in Pliny the Elder's Natural History under the Greek name kuanos (κυανός: "deep blue", root of English cyan) and the Latin name caeruleum. Since antiquity, azurite's exceptionally deep and clear blue has been associated with low-humidity desert and winter skies. The modern English name of the mineral reflects this association, since both azurite and azure are derived via Arabic from the Persian lazhward, an area known for its deposits of another deep-blue stone, lapis lazuli ("stone of azure"). Mineralogy
Azurite is one of two basic copper(II) carbonate minerals, the other being bright green malachite. Simple copper carbonate (CuCO3) is not known to exist in nature. Azurite has the formula Cu3(CO3)2(OH)2, with the copper(II) cations linked to two different anions, carbonate and hydroxide. Small crystals of azurite can be produced by rapidly stirring a few drops of copper sulfate solution into a saturated solution of sodium carbonate and allowing the solution to stand overnight.
Azurite crystals are monoclinic. Large crystals are dark blue, often prismatic. Azurite specimens can be massive to nodular. They are often stalactitic in form. Specimens tend to lighten in color over time due to weathering of the specimen surface into malachite. Azurite is soft, with a Mohs hardness of only 3.5 to 4. The specific gravity of azurite is 3.77 to 3.89. Azurite is destroyed by heat, losing carbon dioxide and water to form black, copper(II) oxide powder. Characteristic of a carbonate, specimens effervesce upon treatment with hydrochloric acid. Color
The optical properties (color, intensity) of minerals such as azurite and malachite are characteristic of copper(II). Many coordination complexes of copper(II) exhibit similar colors. As explained within the context of ligand field theory, the colors result from low energy d-d transitions associated with the d9 metal center. Weathering
Azurite is unstable in open air compared to malachite, and often is pseudomorphically replaced by malachite. This weathering process involves the replacement of some of the carbon dioxide (CO2) units with water (H2O), changing the carbonate:hydroxide ratio of azurite from 1:1 to the 1:2 ratio of malachite:
2 Cu3(CO3)2(OH)2 + H2O → 3 Cu2(CO3)(OH)2 + CO2
From the above equation, the conversion of azurite into malachite is attributable to the low partial pressure of carbon dioxide in air. Azurite is also incompatible with aquatic media, such as saltwater aquariums."
There are currently 118 known chemical elements exhibiting a large number of different physical and chemical properties. Amongst this diversity, scientists have found it useful to use names for various sets of elements, that illustrate similar properties, or their trends of properties. Many of these sets are formally recognized by the standards body IUPAC.
The following collective names are recommended by IUPAC: Alkali metals – The metals of group 1:
Li,
Na,
K,
Rb,
Cs,
Fr. Alkaline earth metals – The metals of group 2:
Be,
Mg,
Ca,
Sr,
Ba,
Ra. Pnictogens – The elements of group 15:
N,
P,
As,
Sb,
Bi.
(Mc
had not yet been named when the 2005 IUPAC Red Book was published, and its chemical properties are not yet experimentally known.) Chalcogens – The elements of group 16:
O,
S,
Se,
Te,
Po.
(Lv
had not yet been named when the 2005 IUPAC Red Book was published, and its chemical properties are not yet experimentally known.) Halogens – The elements of group 17:
F,
Cl,
Br,
I,
At.
(Ts had not yet been named when the 2005 IUPAC Red Book was published, and its chemical properties are not yet experimentally known.) Noble gases – The elements of group 18:
He,
Ne,
Ar,
Kr,
Xe,
Rn.
(Og had not yet been named when the 2005 IUPAC Red Book was published, and its chemical properties are not yet experimentally known.) Lanthanoids – Elements 57–71:
La,
Ce,
Pr,
Nd,
Pm,
Sm,
Eu,
Gd,
Tb,
Dy,
Ho,
Er,
Tm,
Yb,
Lu, Actinoids – Elements 89–103:
Ac,
Th,
Pa,
U,
Np,
Pu,
Am,
Cm,
Bk,
Cf,
Es,
Fm,
Md,
No,
Lr. Rare-earth metals –
ScY, plus the
lanthanoids Transition elements – Elements in groups 3 to 11 or 3 to 12.
