Probably the first
historical references to the use of crystals come
from the Ancient Sumerians (4th millennium BC), who included crystals
in their magic formulas. Crystals were (and are) also used for healing
in
traditional Chinese Medicine, which dates back to at least 5000 years.
The Ancient Egyptians used lapis lazuli, turquoise, carnelian, emerald
and clear quartz in their jewelry. They used some stones for protection
and health, and some crystals for cosmetic purposes, like galena and/or
malachite ground to a powder as the eye shadow. Green stones in general
were used to signify the heart of the deceased and were included in
burials, as it was also found at a later period in Ancient Mexico.
Beautiful
specimens of Lapis
lazuli (left) and Turquoise (right).
(Images taken from external disappeared
references)
The
Ancient Greeks identified quartz with the word "crystal"
(κρύσταλλος,
crustallos, or phonetically kroos'-tal-los = cold +
drop), that is, very cold icicles of extraordinary
hardness. Theophrastus
(c. 371 – c. 287 BC), in his
treatise On Stones
(Περὶ
λίθων), which
was used
as a source for other lapidaries until at least the
Renaissance, classified rocks and gems based on their behavior
when heated, grouping minerals by common properties, such as
amber
and magnetite, which both have the power of attraction.
Probably
the first reference to crystals in Ancient Rome was
reported by Pliny
the Elder
(I Century AD) in his “Natural History”, where he
describes
the windows and greenhouses of the richer inhabitants of the Roman
Empire being covered by crystals of "Lapis
specularis”, the
Latin name for large transparent crystals of gypsum. This dihydrated
form of calcium sulphate was extracted by Romans in
Segóbriga
(Spain) because of its crystal clarity, size (up to one meter) and
perfect flatness. Click on
the image to read its content.
An important part of the economy
of the Roman Hispania during the first
century AD was based on the mining of this mineral and its distribution
through the commercial road that was established (click on the image on
the right), transporting this mineral in carts pulled by oxen to the
port of Cartagonova for its commercial distribution throughout the
Roman Empire.
The vast
amount of mineralogical information
contained in Pliny’s “Natural History”
was preserved
and enhanced in “Book XVI on Stones and Metals”
which
covered the “Etymologiarum" of Isidor of Seville (560-636).
It is
also preserved in the “Lapidarium” of Alfonso X
(1221-1284), a fascinating work by a group of Muslim, Hebrew and
Christian sages from a time when peaceful multicultural collaboration
was demonstrated to be possible.
Ibn Sīnā
"Avicenna" (980-1037),
polymath of Persian origin who wrote
about 450 books, mainly in philosophy and medicine,
classified some
minerals by their
chemical composition. Vannoccio
Biringuccio
(1480-1539), Italian metallurgical, associated shapes and
angles with certain minerals, and Georg
Bauer "Georgius Agricola"
(1494-1555), considered the father
of mineralogy, made the first classification of minerals based on their
physical properties.
However,
it was the unparalleled talent of the Arabian geometers in
investigating the problem of tessellation of two-dimensional space,
which made the most important pre-Renaissance Spanish contribution to
crystallography and geometrical art. The decorative symmetry of the
tiling in the Alhambra
Palace
in Granada (Spain) is
used today to teach symmetry
all over the world.
Mosaics of La Alhambra (Granada, Spain)
The
German
mathematician, astronomer and astrologer Johannes
Kepler
(1571-1630) marveled when a snowflake landed on his coat
showing its
perfect six-cornered symmetry. In 1611 Kepler wrote
”Six-cornered Snowflake” (Latin title ”Strena
Seu de
Nive Sexangula”)
the first mathematical description
of crystals.
In this essay, the first work on the problem of crystal structure,
Kepler asks: Why do
single
snowflakes, before they become entangled with other snowflakes, always
fall with six corners? Why do snowflakes not fall with five
corners or with seven? Despite its modest size,
Kepler’s
essay is remarkably rich in ideas. One of his major discoveries was the
geometry of the packing of spheres (the well known principle of closest
packing in modern structural crystallography). He dealt with the
densest cubical packing, and although he was not aware of the densest
hexagonal packing, Kepler described two less dense packings for
spheres, the hexagonal and the simple cubic. Moreover, starting from
the spherical packings, Kepler drew conclusions about the
parallelohedra, the convex polyhedra which can fill space in a regular
manner, anticipating the conclusions of R.J. Haüy (1784) and
E.S.
Fedorov (1885). Kepler's work contains indirect pointers to the Law of
Constant Angles
for a six-sided snow crystal. Thus one can consider Kepler as a
forerunner of the discoverers of this law (N. Steno, 1669; M.W.
Lomonosov, 1749; Romé de l'Isle, 1783).
In addition
to Kepler’s work, the greatest contribution to
crystallography, paleontology, and geology made during the 17th century
was made by the Danish catholic bishop and scientist Nicolaus
Steno (in
Danish Niels
Stensen, 1638-1686) who
became professor of anatomy at the
University of Padua in Italy, and where he was appointed house
physician to Grand Duke Ferdinand II of Tuscany (1610-1670). During
this decade he made his greatest contributions to science. In
Stensen’s work “De
solido intra solidum naturaliter contento dissertationis prodromus”
he observed
for the first time the fundamental crystallographic Law of the
Constancy of
Interfacial Angles.
Using drawings and two brief sentences, Stensen remarked that although
crystals of quartz (silicon oxide) and hematite (iron oxide) appear in
a great variety of shapes and sizes, the same interfacial angles
persisted in every specimen. This observation, the Law of Constancy of
Angles,
was confirmed and shown to be true for crystals of many other
substances by Romé de l'Isle (1736-1790),
after more than a hundred years later, in 1783. Moreover, Stensen
discussed the growth of crystals in a fluid medium, but for him, this
was only a special case illustrating the main problem of the book: How
are solids of all kinds formed in nature? His answer was: if
a solid body has been produced according to the laws of nature, it has
been produced from a fluid ... either immediately from an external
fluid, or through one or more mediating internal fluids.
At that
time internal fluids accounted for the growth of animals and plants;
sedimentation, incrustation, or crystallization from external fluids
explained the formation of rocks and minerals. It seems obvious that
Stensen's observations on the growth of crystals were also very
important to crystallography.
The French
mineralogist Jean-Baptiste
Louis Romé de l'Isle
(1736-1790) can be considered as one of the creators of
modern
crystallography. He was the author of “Essai
de
Cristallographie”
(1772), the second edition of
which,
regarded
as his principal work, was published in 1783 as “Cristallographie”
in three volumes and an atlas.
His
formulation of the Law
of Constancy of Interfacial Angles was built on the
observations by Nicolaus
Steno (Niels Stensen).
However,
the definitive solid pillar in the construction of
crystallography was set up by the Abbé Haüy (René
Just Haüy, 1743-1822),
professor of the humanities
at the
University of Paris, during the last decades of the 18th century. The
theory of crystal structure elaborated by Haüy
(“Essai
d’un Théorie sur la Structure des
Cristaux”,
1784), based on his discourses on laws of Symmetry, of Rational
Intercepts,
and of Constancy of
Crystalline Form,
does not differ substantially, in its essential points, from the views
prevailing nowadays. By the way, a collection of crystallographic
solids given by Haüy to the Galician mathematician José
Rodríguez González
(1770-1824) was used by the
crystallographers Augusto
González de Linares
(1845-1904) and Laureano
Calderón Arana
(1847-1894) who established what probably was the first (1888)
Chair of Crystallography in a European University (Santiago de
Compostela).
The
previous observations and the mathematical developments introduced
during the 19th Century
brought us to the modern structural crystallography... In 1830 the German
physician Johann
Friedrich Christian Hessel
(1796-1872) proved that, as
a consequence of Haüy’s Law of Rational Intercepts,
morphological forms can combine to give exactly 32 kinds of crystal
symmetry in Euclidean space (32
point groups),
since only two-, three-, four-, and six-fold rotation axes can occur.
In 1848 the French physicist Auguste
Bravais (1811-1863)
discovered
that there are 14 unique lattices (Bravais
lattices) in three
dimensional crystalline
systems, correcting the previous scheme (15 lattices) conceived by the
German Moritz
Ludwig Frankenheim
(1801-1869) three years before.
Finally,
the 14
Bravais lattices
and the 32 point groups
were the constraints between which the eminent Russian crystallographer
Evgraf Stepánovich Fedorov(1853-1919), and independently
the German mathematician Arthur
Schoenflies (1853-1928),
deduced in 1890-1891 the
230 possible space
groups that restrict the mutual arrangement of building
units (atoms, ions, molecules) inside crystals.
Interested readers can have
access to an
extensive and commented chronology on crystallography and structural
chemistry through the
work done by M.A. Cuevas-Diarte and S.
Alvarez Reverter.
All these principles are the pillars on which the modern structural
crystallography was built, the crystallography that appeared after
X-rays discovery.