K-feldspar Research Articles

Source of Palm Spring Sediments, Imperial Valley, California: ABSTRACT

End_Page 1764------------------------------Sands of the Palm Spring Formation are similar to those of the Colorado delta and those deposited in Lake Mead. All are very well sorted, and have similar median diameters and mineral composition. Cretaceous Foraminifera (reworked) which are widespread in the Palm Spring occur in the delta sands. Various primary structures characteristic of the Palm Spring are present in delta sediments. Both groups of sediments contain important amounts of volcanic and carbonate rock fragments and potash feldspar whereas plagioclase, hornblende, and augite are minor. The source indicated by this assemblage is the Great Basin-Colorado Plateau area rather than the Peninsular Range. The latter area probably supplied some coarse arkosic sands and gravels interfingering in the west with the fine sands, si ts, and clays but it is probable that most of the Palm Spring Formation is Pleistocene delta sediment. End_of_Article - Last_Page 1765------------

Sedimentary Environments in the Malacca Strait, Malaysia: ABSTRACT

A preliminary investigation of the waters and bottom sediments in the Malacca Strait and southern portion of the Andaman Sea, made in 1961 by the U. S. Naval Oceanographic Office, resulted in the collection of bottom sediments as well as salinity, temperature, and water transparency observations at 23 stations. Current measurements were made at selected sites for periods of 24 to 36 hours. The Malacca Strait is a narrow, shallow passage between the Malay Peninsula and Sumatra with oceanographic and bottom sediment characteristics closely related to the strong currents, debouching rivers, climatic variation, and the close proximity of bordering land masses. The strait assumed its present configuration as a result of the post-glacial rise of sea level which drowned the Sund Shelf. The strait is located in a typical equatorial climate although the monsoonal effects are not as severe as in the more open neighboring areas. A northwest current flow, essentially tidal, prevails in the strait throughout the year, and is largely responsible for the hydrographic and oceanographic conditions in the area. Surface salinities and temperatures are found generally to be lower than in the surrounding seas. A wedge of cold, high-salinity bottom water extends from the Andaman Sea into the Strait. Bottom sediments primarily consist of muddy sands, with large areas of mud occurring in the vicinity of debouching rivers and in the Andaman Sea Basin. Calcium carbonate, primarily in the form of mollusk shells and foraminiferal tests, and organic carbon are found only in minor am unts in the Strait. Higher concentrations of calcium carbonate generally were associated with the finer sediments of the Andaman Sea, while the higher concentrations of organic carbon were found in the vicinity of debouching rivers. The noncalcareous detrital fraction is dominated by quartz, with minor amounts of orthoclase and plagioclase feldspars. The heavy mineral suite is complex due to the varied geology of the bordering land areas. The heavy minerals present consist primarily of leucoxene, ilmenite, magnetite, biotite, and amphiboles. End_of_Article - Last_Page 346------------

On the structure and petrography of the Ipernat Dome, western Greenland

A well exposed area with a Precambrian gneiss dome was investigated. Photogeological methods were used to a great extent; the aerial photographs are reproduced and a geological map, scale 1:75000, is presented. The folding appears to be rather gentle. For the greatest part the rocks crystallized under the conditions of hornblende-granulite subfacies. Subsequently, a large proportion of them metamorphosed retrogressively. Chemical analyses of three granodioritic and quartz dioritic rocks and one garnet are presented. Refraction indices and unit cell dimensions of three garnets, optical properties of some pyroxenes and triclinicity values of some potash feldspars are given. Twenty determinations of the sodium and potassium content of representative samples indicate that potassium is not concentrated in the gneiss core of the dome.

Analysis of Equilibrium in Garnet-Biotite-Sillimanite Gneisses from Quebec

An analysis is presented of equilibrium in six specimens of garnet—biotite—sillimanite—plagioclase—potash feldspar—quartz … gneiss from a metamorphic terrain in south-western Quebec. A nearly uniform Ti content of biotite may be accounted for by an equilibrium (a) involving biotite, sillimanite, quartz, garnet, potash feldspar, and H2O. The nature of the distribution of Fe and Mg between garnet and biotite may be accounted for by another equilibrium (b) involving the same mineral suite, or by a simple exchange equilibrium (c) involving only garnet and biotite. The distribution of Mn between garnet and biotite is accounted for by an exchange equilibrium (d). A nearly uniform value of the ratio Ca content of plagioclase/Ca content of garnet may be accounted for by an equilibrium (e) involving plagioclase, garnet, sillimanite, and quartz. A proposed equilibrium (f) involving biotite, quartz, ilmenite, potash feldspar, sillimanite, and H2O conflicts with equilibrium (a) and was evidently not established in the gneisses. The factors governing the Ca content of biotite remain largely unknown. Some of these equilibria form potential indicators of relative geologic temperature, pressure, and chemical potential of H2O.

Radioactivity of metamorphic rocks in Onnagawa district, Niigata Prefecture

This work is a test for the application of radioactive survey to geological survey in field. This survey is applied to the contact metamorphic rocks which occured by the granite intrusion into the paleozoic formation in Onnagawa district of northern part of Niigata Prefecture. The radioactivity of this metamorphic rocks are determined by the contents of potash feldspar in the rocks. Potash feldspar occurs in nearest part from granite intrusion, which are most strongly metamorphosed.

Petrological studies on the metasomatic syenites in Japan. Part 1. Syenites of the Cape of Ashizuri, Kôchi Prefecture

The syenites of the Cape of Ashizuri are fine to coarse-grained, and composed mainly of albite to oligoclase, highly sodic orthoclase, ferropargasitic amphibole, and green biotite. They are transitional to the older biotite granite and intruded by the younger biotite granite. From field evidences and petrographic characters, it is considered that the syenites have been derived from the older granites by the metasomatic action of alkali solution, originated probably from the younger granite magma. The addition of Al2O3, Fe2O3+FeO, CaO and Na2O to the original rock is accompanied by the subtraction of SiO2 and K2O, slight increase in oxidation ratio, and high decrease in Or content in potash feldspars. The syenites of the Cape of Ashizuri are considered to have been formed at comparatively higher temperature and lower oxygen pressure than some syenitic rocks in southwestern Japan.

Basalt from a Deep Well in Lawrence County, Indiana

An amygdaloidal, ophitic, and slightly porphyritic basalt occurs beneath Cambrian or Precambrian sedimentary rocks in a deep well in Lawrence County, Indiana. The rock has been highly altered and contains more than 35 per cent chlorite. Many of the plagioclase $$(An_{56})$$ microlites and small orthopyroxene crystals have been chloritized, but clinopyroxene, which typically is found as phenocrysts, is unaltered. Plagioclase $$(An_{46-62})$$ phenocrysts have been altered to muscovite, and large orthopyroxene crystals have been replaced by biotite. The alteration of chlorite has produced pumpellyite. Quartz, calcite, dolomite, analcite, potash feldspar, chlorite, and pumpellyite fill veins and cavities. Sparse magnetite and secondary pyrite are present, and red iron oxides are abundant in the upper part of the basalt. The basalt from Lawrence County is very similar texturally, mineralogically, and chemically to the Precambrian Keweenawan flows of Michigan and to a Precambrian augite andesite microporphyry f...

Comparison of potassium chloride, bicarbonate, and metaphosphate, and calcined orthoclase, as sources of potassium for white clover

Abstract KCl, KHCO3, KPO3, and a calcined potash feldspar, were compared as sources of K in a pot experiment with a K-deficient yellowbrown loam, a soil from andesitic volcanic ash (the New Plymouth black loam), using white clover as the test crop. KHCO3 and KPO3 gave responses similar, in terms of dry matter yield and K content of the clover, to those given by KCl, and uptake of K was just as rapid. Calcined feldspar gave only a very slight response. Losses of cations by leaching from the mineral soil were small for all treatments, particularly for K, and there was some indication that lower losses occurred from the KHCO3, and especially the KPO3, treatments, as compared with the KCl. Exchangeable K values reached very low levels on all treatments during the period of the experiment, and this was reflected in low levels of K in the plant tops. This lowered K content in the plant was to some extent counterbalanced by an increase ill the content of Ca and Mg. In a subsidiary pot experiment calcined feldspa...

PETROLOGICAL STUDY OF THE THERMALLY METAMOR-PHOSED ROCKS SURROUNDING THE TANOHATA GRANITIC MASS, NORTHERN KITAKAMI MOUNTAINLAND, NORTHEASTERN JAPAN (I)

Abstract: Paleozoic formation, Jurassic formation, lower and upper Cretaceous formation, Paleogene formation and granitic rocks are widely exposed in this district. The geological succession and the igneous activity are shown in Table 1. Granitic masses are divided into two groups. The first group consists of granitic stocks such as the Taro, Kurumihata, Jofutsumori and Ojiri masses, and the second group consists of granitic masses such as the Tanohata, Hashikami and Miyako masses. The Tanohata granitic mass is divided into two rock facies, i.e., the Otomo and Moichi types. The Otomo type is composed of coarse-grained trondjhemite and granodiorite, and the Moichi type is composed of medium-grained granodiorite, quartz monzonite and quartz diorite. The thermal metamorphosed rocks mentioned in this paper develope around the Tanohata granitic mass of the second group and are derived mainly from sediments of the Paleozoic and lower Cretaceous formations. The contact aureole around this granitic mass is divided into the following three zones: biotite slate zone........western and eastern sides cordierite spotted slate zone....western and eastern sides, and a part of the roof-pendant high grade zone........western side and roof-pendant The biotite slate and cordierite spotted slate zones are characterized by the existence of biotite and cordierite respectively. In the cordierite spotted slate zone, cordierite begins to occur prior to andalusite. The high grade zone is characterized by the coexistence of cordierite and andalusite and/or sillimanite with potash feldspar. Most of the rocks of the high grade zone, especially laminated and banded hornfelses, resemble the rocks of the Ryoke metamorphic terrain in feature and mineral paragenesis. Sillimanite is rare, and forms fibrolitic needles around biotite and andalusite crystals in the hornfelses of the western side of the granitic mass. On the contrary, sillimanite needle replaces andalusite in some hornfelses of the roof-pendant. It seems that andalusite-sillimanite transition (the first sillimanite isograd) takes place in the hornfelses of this aureoles, where the coexistence of potash feldspar and sillimanite (the second sillimanite isograd) is also found. From such relation, it seems that the first sillimanite isograd coincides with the second sillimanite isograd in this contact aureole. This is a distinct difference from the Ryoke metamorphic terrain, and this may be due to the difference in the rock pressures of the two areas. The rocks of this aureole contain few sillimanites, andalusites and garnets compared with those of the Tono and Senmaya contact aureoles in the Kitakami Mountainland. On the other hand, potash feldspar are present generally in large amount in the rocks of this aureole. Difference of contents of metamorphic minerals and mineral paragenesis among their contact aureoles may be due not to the physical condition, but to the chemical composition of original rocks. Potash feldspars were studied optically and by X-ray method. Potash feldspars in the rocks of the high grade zone show monoclinic symmetry. The crystallization temperatures of potash feldspars were also examined by Barth´s method. Ferric-ferrous ratios (Fe2O3/Fe2O3+FeO) of biotites in the high grade zone are 0.05 to 0.07 and resemble those of the Senmaya aureole and the Ryoke metamorphic terrain, but they are smaller than those of the Abukuma metamorphic terrain. Lastly, metasomatism was discussed from the compositional variation of major and minor elements. In some rocks of the high grade zone, it seems probable that potassium was introduced from granitic rock.

Abrasion Effects on Arkose Mixtures

ABSTRACT Mixtures of quartz and potash feldspar grains, varying in size, were placed in a group of oscillating tubes for a maximum of 30 hours. The samples were analyzed at 10 hour intervals and weight loss computed for each component. It was found that abrasion rate changes with different size combinations of quartz-feldspar components. Abrasion was significant in some mixtures which contained relative sizes normally found in nature. The theoretical effect of abrasion on a hypothetical sediment is considered, based upon the experimental evidence. It appears reasonable that abrasion, when considered as occurring along with other size reduction factors, is of considerable importance.

Quartz and Feldspar Content in South Platte, Platte, and Missouri River Sands

ABSTRACT The quartz and feldspar content was determined for 70 stream sand samples from the South Platte, Platte, and Missouri rivers. Between the headwaters of the South Platte and Denver, Colorado, the changes in quartz and feldspar content are erratic, but between Denver and the junction of the Missouri and Mississippi rivers, quartz increases about 10 percent, potash feldspar decreases about 11 percent, and plagioclase feldspar increases about 1 percent. If these results are combined with those of Russell (1937) and Willman (1942) for the Mississippi River, quartz increases 19 percent, potash feldspar decreases 13 percent, and plagioclase feldspar decreases 3 percent between Denver and the Gulf of Mexico. The average of 11 stream sands shows no variation of quartz content with grain size, but potash feldspar content decreases with decreasing grain size, and plagioclase feldspar increases with decreasing grain size. The average of 7 gruss samples shows the same trends; hence, weathering and the grain size of the various minerals in the original rock are believed to strongly influence the distribution of quartz and feldspar in the various size fractions. The difference between the quartz and feldspar content of the stream and gruss samples indicates that the feldspar content decreases quickly after the gruss material enters the stream. Pettijohn's (1957) conclusions that the feldspar content of stream sands is reduced rapidly in high-gradient streams, but is lost slowly in low-gradient streams seems to hold in the South Platte, Platte, Missouri, and Mississippi river drainage system.

Postdepositional alteration of sandstone minerals under acidic reducing conditions; a factor in the interpretation of sandstone texture

Notes that development of secondary clay minerals from potash feldspar and other detrital minerals in the Carboniferous (Namurian) subgraywacke sandstones of southwest Derbyshire, England, may have occurred in a highly acid reducing environment such as has been postulated for postdepositional alteration of ilmenite in unconsolidated sediments.

The Metasomatic Origin of the Potash Feldspar MegaCrysts in the Granites of Southwest England

Evidence is presented to show that the big potash feldspars in the aplite-pegmatite complex at Tremearne and in the Carnmenellis granite in western Cornwall have grown in solid or nearly solid rock. It is considered that the rocks present before metasomatism were aplitic and that these rocks have been permeated by a fluid phase containing potassium; there is evidence that this dispersed phase caused the metasomatism and re-crystallization of the aplitic rocks to produce porphyritic granite and pegmatite. These conclusions can be extended to other granitic rocks of southwest England.

Fusion of Potash Feldspar and the Leucite Problem

It is said that under the equilibrium condition, potash feldspar decomposes into leucite and melt at about 1150°C, which is within the temperature range for the firing of porcelain. Therefore, it is an important problem to know whether the leucite is actually formed in porcelain bodies containing potash feldspar during the firing process.Potash feldspar specimens fired at 1150°-1450°C, or soaked at 1260°C for 4hrs and kept at 1300°C for 10.5hrs, were examined by means of polarization microscope and X-ray diffraction (Fig. 1.), but with a result that no leucite was detected in the fired specimens. Furthermore, specimens consisting of potash feldspar and quartz and -or kaolin were examined by the same way without being able detect in their fired specimens either.From the results obtained it was concluded that the potach feldspar does not decompose leucite and melt, but melts completely into glass, so far as it is fired with the schedule used in the porcelain bodies.The fact can be explained as follows: If the potash feldspar begins to melt at higher temperature than T2 (Fig. 3A), it does not decompose into leucite and melt which are coexsting in the most stable condition, but usually melts into a glass, the only one which is the next stable. These relations between the phases formed with temperature and time are infered as Fig. 3B.The compositions of porcelain bodies containing potash feldspar are usually in the shadowing range of K2O-Al2O3-SiO2 diagram (Fig. 4.). From the diagram it is apparent that the leucite is formed only in the very high potash feldspar bodies which are higher in K2O than that of N-Z line in Fig. 4. Therefore, in the porcelain bodies, leucite is hardly formed even if they are fired under the equilibrium conditions.

Science in the ceramic industry

It is almost 180 years since Josiah Wedgwood reported to the Royal Society some of the first results of systematic research into ceramics ever to be conducted. The art of ceramics has been described (Bradstreet 1958) as a system in which ‘minerals of inconstant composition and doubtful purity were exposed to immeasurable heat long enough to carry unknown reactions partly to completion, forming the hetero­geneous non-stoichiometric materials known as ceramics’ and it has also been suggested that this situation has been little changed by a more formal scientific approach. It is certain that Wedgwood conducted his remarkable systematic series of experiments in this context—his notebooks record nearly 7000 trials—and, as J. W. Mellor (1915) has pointed out, ‘it is difficult to realize the state of chemistry at the time of Josiah Wedgwood. There was no Dalton’s Atomic Theory. . . and chemistry was autocratically dominated by old King Phlogiston’. Nevertheless, Wedgwood’s work is one of the great foundation stones of the English ceramic industry, and within a hundred years the basic formulae for most indi­genous whiteware bodies were established. The introduction of the white burning Devonshire clays, and calcined flint (cryptocrystalline quartz) is generally at­tributed to Thomas Astbury, who is also credited with some more sophisticated experiments on the use of lead ores in glazes. The age-old technique of ‘potting’ or shaping the plastic clay was supplemented about 1730 by the introduction of slip casting, in which a ‘slip’ or aqueous suspension of clay and minerals is cast into a porous mould, now plaster of paris but originally prefired porous ware. These processes of potting and slip-casting remain a challenge to the applied physicist even today. Another remarkable development of this period was the production of a body containing calcined animal bone—the forerunner of the quite characteristic English bone china, which is one of the strongest of all traditional ceramic materials. English earthenware now consists of china clay, ball clay, silica (calcined flint) and Cornish stone, the last being a felspathic mineral (generally containing some fluorspar) which serves as a flux. The starting materials may include 50 to 60% of clay, 30 to 35% flint, the remainder being Cornish stone. When fired, it is a microporous material, consisting of crystalline phases bonded by a complex glassy phase: the pore and grain size may be of the order of 0·1 μ or less. Bone china contains about 50% of animal bone, 25 to 30% clay and the remainder Cornish stone. Porcelain in the Continental tradition, in which potash felspar is used as a flux, is not a major feature of the English domestic ware industry, but electrical porcelain, as used in the power distribution industry, and some chemical ware, are essentially based on clay, quartz and felspar. Bone china and most porcelains are fully vitrified and effectively non-porous. The production of ware in all these media constitutes the largest branch, in the economic sense, of the ceramic indus­try of this country, and the articles produced are strikingly characteristic and in some ways unique.

Nature and mode of weathering of soil‐potassium reserves

AbstractIn most partially weathered mineral soils only a small part of the total potassium is readily exchangeable to other ions; the bulk occurs in non‐exchangeable (or difficultly‐exchangeable) forms in potash feldspars, micas and micaceous clays, all of which are potential sources of potassium for plants.Some of the principles underlying the weathering processes in feldspars, trioctahedral and dioctahedral micas are discussed. The ease with which freshly cleaved potash feldspar releases potassium to water cannot be taken to indicate that the feldspar weathers easily; in soil the feldspar is protected by a surface covering of its own decomposition products. Trioctahedral micas are less stable to weathering than dioctahedral micas, particularly during the early stages of potassium depletion; the stabilities of these two main groups of micas differ more than can be accounted for in terms of ferrous iron contents. For micas and micaceous clays the relationships between parent lattices and weathering products must depend very largely on the extent to which layer‐charges have decreased on weathering. As more becomes known about the potassium‐containing minerals which occur in soils, we should be better able to understand the factors which influence the long‐term ability of soils to supply potassium to crops.

Trace lead in potash feldspars associated with ore deposits

The amount of trace Pb in potash feldspars can be correlated with the Pb ore deposits associated with igneous rocks. The Pb content of K feldspars separated from several quartz monzonite intrusives of the Basin and Range province has been determined spectrochemically. Samples were collected from the Tintic, West Mountain (Bingham), Park City-Little Cottonwood, and Iron Springs mining districts in Utah, and from the Robinson mining district and the Whitehorse Pass area in Nevada.

X-ray study of the structure of moonstones

X-ray studies on three different types of moonstones, namely, Ceylon, Coimbatore and Korean varieties have been made by single crystal rotation and Weissenberg methods. The results are consistent with the explanation that the triclinic soda-feldspar crystallites which has segregated out of monoclinic potash feldspar are twinned according to albite law, in the former two, while the twinning is according to pericline law in the latter moonstone. The view is put forward that the narrowing down of the differences, firstly of thea-axial dimension between the soda-feldspar and potash feldspar phases, and secondly between the lattice angles of the two feldspars result in pericline twinning of the soda-phase, while albite twinning results when the sodaphase demands full triclinic symmetry and the potash phase has thea-axial dimension corresponding to that of orthoclase. The detailed features of the Weissenberg X-ray diagrams of Korean moonstones reveal that there exist in it a monoclinic potash phase and a pericline twinned triclinic sodaphase, in agreement with the results obtained by Chao and Taylor. X-ray results also indicate that the lattice angleγ of the triclinic soda-phase in these moonstones is very nearly equal to 90°.

Chess-Board Albite from New Brunswick, Canada

AbstractChess-board albite is described and theories on its origin outlined. A new occurrence from New Brunswick, Canada, is noted and certain features of the chess-board albite, discussed which fit the theory that it results from two processes, namely metasomatism of potash feldspar to soda feldspar, and deformation. This hypothesis is applied to British localities.

Potash felspars in some metamorphic rocks

Potash felspars in the Akka metamorphics (contact metamorphic rocks), several other metamorphics and granites are studied optically and by the x-ray powder method. Triclinicity values (Δ) in potash felspars of the Akka metamorphics show monoclinic symmetry, not only in orthoclase zone (higher part of amphibolite facies), but also in cordierite zone. Potash felspars in hornfelses close to granite mass seem to show diffuse reflection and large optic angle. In other metamorphic terrains, potash felspars show extremely low triclinicty values, while those in the Hida gneiss, as well as the Hida granite, show large triclinicity values. From these results, the relations between symmetry change of potash felspar and metamorphism are discussed. From the albite molecular percent in some alkali felspars, the temperature of potash felspar formation is determined by the Barth's method.