Geoscience Reference
In-Depth Information
pyramidal termination. When the solution contained NaHCO
3
,CO
2
, and some real-
gar, very little quartz was obtained. It was probably Daurree
[9]
, a French mineralo-
gist, who first used a steel tube to synthesize quartz and wollastonite at about 400
C
with water as a solvent. The most important aspect of his experiments was the pres-
sure balance he introduced for the first time. The starting substances were taken in a
sealed glass tube with water as a mineralizer, and this glass tube was placed inside a
steel tube. The space between the glass tube and steel tube was filled with water. He
carried out a series of experiments with this design and a varied concentration of the
starting materials to obtain several other minerals. Similarly, he conducted experi-
ments on the recrystallization of feldspars, micas, and pyroxenes.
Daurree's other significant contribution was his attempt to use natural hot spring
water from Plombieres as a mineralizer and this led to the deposition of a small
quantity of quartz over 2 days. In addition, he treated kaolin with Plombieres water
under hydrothermal conditions and obtained feldspar and a small amount of quartz.
Here, it is interesting to note that, after the discovery of hydrothermal activity in
the deep sea on the Galapagos during the 1970s, active research is going on using
the natural submarine hydrothermal vent fluid to study the origin of life (organic
synthesis). This led to the establishment of the relation between the submarine
hydrothermal activity and rich mineralization of a very wide spectrum from native
elements to sulfides, oxides, and so on
[10
12]
.
The literature survey on the early
hydrothermal research shows that several attempts were made to transform zeolite
minerals and kaoline in the nineteenth century
[7
2
13]
, but it was only during
1940 that Barrer
[14]
succeeded in synthesizing zeolite for the first time, that is,
analcime, using the hydrothermal technique. Although Deville St. Claire (1857)
attempted to transform bauxite into corundum under hydrothermal conditions using
NaOH as mineralizer, the experimental results were not definite. Perhaps, he was
the first one to use a mineralizer other than water
[15]
. In fact, many of the earlier
workers, including von Chroustshoff
[16]
, found that the glass tubes they were
using were frequently attacked under hydrothermal conditions. However, they do
not mention anything about precautions taken in this regard, as they were more
concerned in obtaining a product corresponding to some natural minerals. During
1873, von Chroustshoff first proposed the gold lining of steel autoclaves to prevent
corrosion. By introducing gold lining for the steel autoclaves, he could achieve
a temperature of 350
C to synthesize the tridymite phase of quartz and increase
experimental duration
[17]
.
With the introduction of steel autoclaves along with noble metal linings, the
tendency to reach higher pressure
10 atm
began. However, the majority of the works up to 1880 remained pertaining to quartz,
feldspar, and related silicates. Thus, many of the earlier authors even define hydro-
thermal technique as the “one used in the synthesis of silicates.” In 1880, Meunier
[17]
carried out an experiment using water vapor passed over AlCl
3
and Mg con-
tained in an open tube, heated to a low red heat and obtained mainly spinel. In some
parts of the tube, he even observed tiny crystals of periclase and corundum.
Followed by this work, Hannay
[18]
claimed to have synthesized artificial
diamond by the hydrothermal technique. Similarly, Moissan
[19]
also claimed to
temperature conditions than the usual 5
