The stability relations of the silica minerals

Fenner, C. N.

doi:10.2475/ajs.s4-36.214.331

Cited by 159 publications

(73 citation statements)

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“…Its presence may mean that water vapor pressures were lower than those that prevailed during the first stage of crystallization, but it does not place useful limits on the temperatures. From a pure SiO2 melt, stable cristobalite forms above 1,470° C; below that temperature, tridymite or quartz is the stable phase (Fenner, 1913). Experimental and thermodynamic evidence suggests that if tridymite is not formed, only quartz should form from a pure melt below about 1,000°C (Mosesman and Pitzer, 1941, table 8, fig.…”

Section: Geology and Volcanic Petrology Lava Mountains San Bernardimentioning

confidence: 99%

Geology and volcanic petrology of the Lava Mountains, San Bernardino County, California

Smith¹

1964

Professional Paper

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Section: Geology and Volcanic Petrology Lava Mountains San Bernardimentioning

confidence: 99%

Geology and volcanic petrology of the Lava Mountains, San Bernardino County, California

Smith¹

1964

Professional Paper

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“…tridymite underwent subtle and sometimes continuous changes which, in effect, reconcile all the different temperatures reported in the literature (Table 1). The major transition, between 159-165 ~ C, clearly represents one of the most well-documented phase transitions for tridymite, first reported by Fenner (1913). The transition hysteresis observed on cooling has been noted previously (Shahid and Glasser 1970;Nukui etal.…”

Section: Discussionmentioning

confidence: 57%

A study of the thermal behavior of terrestrial tridymite by continuous X-ray diffraction

Smelik

Reeber

1990

Phys Chem Minerals

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Abstract. Phase transition behavior of two types of terrestrial tridymite; crystals from Topaz Mountain in the Thomas Range of northwestern Utah and Smith Peak in Plumas County, California; were investigated. The Topaz Mtn. samples were characterized at room temperature using optical, X-ray diffraction (Debye-Scherrer, rotation, and Laue), and transmission electron microscopy (TEM) methods. Least-squares refinement of the powder data yielded an orthorhombic cell with a= 17.072 ~, b=9.923 ~, and c=16.291 ~. The tridymite is designated PO-2 (nomenclature of Nukui and Nakazawa 1980). This material is complexly twinned and has severe stacking disorder parallel to [001]. Additional Xray experiments were performed on one Plumas County crystal and four Topaz Mtn. crystals during heating from room temperature to a minimum of 320 ~ C with one run attaining a maximum temperature of 532 ~ C. Crystal to crystal behavior was somewhat variable suggesting kinetic barriers to transition controlled by the detailed structural state of each crystal.The Laue results indicated that the transition behavior of these multiple twinned tridymites could be conveniently divided into two classes: discontinuous and continuous. The discontinuous diffraction effects were generally associated with major structural transitions. Continuous diffraction effects involved gradual structural distortions of the tridymite framework that occurred over discrete ranges of temperature. Upon cooling, many of the minor effects were not reversible while the major transitions were reversible with some temperature hysteresis. Comparison of initial and final diffraction patterns indicated that the starting and ending structures were very similar but not identical. From the five experiments, three distinct patterns emerged based on the major transitions observed: Type I behavior (Topaz Mtn.) characterized by three major changes at 175-187 ~ C, 283-302 ~ C, and 348-352 ~ C, Type II behavior (Plumas * Present address: Department of Earth and Planetary Sciences, The Johns Hopkins University, Baltimore, MD 21218, USA Co.) characterized by one major transition between 283-295 ~ C, and Type III behavior (Topaz Mtn.) characterized by one major change between 159-165 ~ C.

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“…In certain cases no one would question the value of the contribution made to our knowledge by phase equilibrium studies, one very well known example being the study of the stability relations of the silica minerals carried out by Fenner (1913).…”

Section: Discussionmentioning

confidence: 99%