An original and detailed study focusing the petrography of evaporites from the Late Aptian deposits exposed in the eastern and southern São Luís-Grajaú Basin is presented herein, with the attempt of distinguishing between primary and secondary evaporites, and reconstructing their post-depositional evolution. Seven evaporites phases were recognized: 1. chevron gypsum; 2. nodular to lensoidal gyp...

Background Gypsum, or calcium sulfate dihydrate, (CaSO4 l 2H2O) is the major component of drywall, or gypsum board, core. It is a naturally occurring mineral, deposited largely as a result of the evaporation of water in ancient inland seas, which contained large amounts of dissolved gypsum. For example, the evaporation of a typical 20,000 gallon residential swimming pool filled with seawater wi...

The rate of hydration influences many important physical properties of gypsum. Previous research examined the rate of gypsum hydration and related this to compressive strength and microstructure development using BET specific surface area analysis. The analysis of gypsum porosity in combination with BET surface area and rate of hydration remains to be done. In the present study, mesoporosity is...

This paper reviews the main methodologies and techniques that have been used to characterize gypsum in soils, especially in gypsiferous soils of semiarid and arid regions and range from the identification of gypsum in soil surveys in the field to the study of gypsum in the laboratory. Many methods of gypsum identification and determination have been developed, each one with its own limitations....

Gypsum is hydrated calcium sulfate (CaSO 4 • 2H 2 O), and is often marketed as a soil " conditioner " for improving soil " tilth. " Compared to most other calcium-rich soil amendments, such as limestone, gypsum is relatively soluble in water, dissolving up to 2 g per liter. The solu-bility of gypsum, when either incorporated or surface applied, permits a quick release of calcium (Ca 2+) and sul...

In order to determine the feasibility of manufacturing wood-gypsum and wood-gypsum-cement particleboards, the hydration reactions of four Eastern Canadian wood species with gypsum and Portland cement were studied. The compatibility of hot water extracted and raw wood particles with both gypsum and a gypsum-Portland cement mixture were determined for jack pine, balsam fi r, aspen and white birch...

Amelioration of subsoil acidity using gypsum (CaS04.2Hz0) or lime (CaC03) was studied on sandy textured soils with low water holding capacity in a low rainfall environment. Field trials were established in 1989 at two sites on yellow sandplain soils to investigate whether different rates, sources and combinations of gypsum and lime application could be used to increase wheat and lupin yields. G...

Introduction: The OMEGA instrument on Mars Express has recently detected the largest gypsum deposit on Mars within the north polar sand sea [1]. Here we discuss the unique geologic context and origin of this evaporite deposit. Gypsum on Earth and Mars: Gypsum is a hydrated Ca-sulfate (2H 2 O • CaSO 4). Though gypsum can be formed, for example, as a hydrothermal deposit [e.g., 2] or as an altera...