Problems of crystal growth in building materials

Lea, F. M.; Nurse, R. W.

doi:10.1039/df9490500345

Cited by 16 publications

(2 citation statements)

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“…For the development of short prismatic forms, this inhibition has been related to the presence of organic compounds (e.g. Lea and Nurse, 1949;Van Rosmalen et al, 1976) and less commonly to a high salinity (Cody, 1976) or a high pH (Kirov, 1980). The development of lenticular forms, irrespective of whether (only) a selective growth inhibition is involved, has also been attributed to the presence of organic substances (Cody, 1979;Cody and Cody, 1988) or sodium chloride (Deicha, 1943, p.157;1946), as well as to high Ca/SO 4 ratios (Kushnir, 1980).…”

Section: Lenticular Crystalsmentioning

confidence: 98%

Distribution patterns of gypsum and kalistrontite in a dry lake basin of the southwestern Kalahari (Omongwa pan, Namibia)

Mees

1999

Earth Surf. Process. Landforms

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The deposits of the Omongwa pan, southwestern Kalahari, Namibia, are partly gypsiferous and locally contain small amounts of kalistrontite. The distribution patterns of gypsum (CaSO 4 .2H 2 O) and kalistrontite (K 2 Sr(SO 4 ) 2 ) are mainly determined by groundwater depth and by the lithological composition of the deposits. The latter determines the hydraulic conductivity for saturated and unsaturated flow and therefore controls the depth of the interval within the deposits where evaporation and mineral precipitation can take place. Other factors that affect the distribution of the evaporite minerals are the patterns of groundwater flow within the basin and the occurrence of a redistribution of salts during short flooding stages.Gypsum occurs as crystals of four distinct morphological types, which each developed in different conditions: prismatic crystals formed both as subaqueous precipitates and as crystals that developed within the sediment matrix of a brine-saturated surface layer; sub/euhedral tabular crystals formed within brine-filled macropores; hemi-bipyramidal crystals formed in a nearly permanently brine-saturated part of a subsurface horizon (phreatic zone), as the product of recrystallization of an older gypsum occurrence; and lenticular crystals formed by intrasediment growth in the vadose zone. The development of these morphological types of gypsum crystals is marked by differences in the differential inhibition of growth of the various crystal forms. The further growth of lenticular crystals, which are most strongly affected by differential growth inhibition, is still characterized by a difference in degree of inhibition between the {111} and {103} forms, expressed as a change in orientation of the plane of flattening.

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Section: Lenticular Crystalsmentioning

confidence: 98%

Distribution patterns of gypsum and kalistrontite in a dry lake basin of the southwestern Kalahari (Omongwa pan, Namibia)

Mees

1999

Earth Surf. Process. Landforms

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“…This seems to be the most widespread prismatic form of gypsum, but there appear to be hardly any previous references to it in arid-zone soils. Previous records are from building materials (Lea & Nurse, 1949), artificial media (Wied & Syrojezkina, 1965;Barta et al, 1971;Edinger, 1973;Liu & Nancollas, 1973;Cody & Plates 10-18. Shanks, 1974;van Rosemalen et al, 1976;Cody, 1979), sea water evaporation (Barcelona & Atwood, 1978), sabkhas, playa lakes and derived crusts (Carenas et al, 1982) and in secondary products of pyrite oxidation (Grattan-Bellew & Eden, 1975;Bullock et al, 1985).…”

Section: Prismatic Pinacoidal Crystalsmentioning

confidence: 99%

Gypsum crystals in soils

Jafarzadeh

Burnham

1992

Journal of Soil Science

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Gypsum is deposited in soils by capillary rise from water tables (per ascensum), or by movement downwards following incomplete wetting (per descensum). Both these situations were reproduced in artificial columns using a wide range of soil materials. Two soil profiles formed per ascensum on Bahrain Island and two per descensum in Iran were also studied. The size, shape and arrangement of gypsum crystals were determined by optical examination of specimens and thin sections and by using the scanning electrod microscope. A comprehensive scheme for their description is outlined. Tabular, prismatic, lenticular, acicular, fibrous, tubular and granular forms were found, often modified by features produced by partial solution and subsequent resumption of crystallization. The form of gypsum crystallization changes intricately in space, and is often ephemeral in time, making it difficult to draw firm conclusions linking crystal shape to particular environments or soil types.

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Nývlt

Ulrich

1995

Admixtures in Crystallization

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Problems of crystal growth in building materials

Cited by 16 publications

References 0 publications

Distribution patterns of gypsum and kalistrontite in a dry lake basin of the southwestern Kalahari (Omongwa pan, Namibia)

Distribution patterns of gypsum and kalistrontite in a dry lake basin of the southwestern Kalahari (Omongwa pan, Namibia)

Gypsum crystals in soils

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