Iranian Journal of Crystallography and Mineralogy
Year:2002 | Volume:10 | Issue:1|Papers Count:7

Shahmirzad village is located on the southern parts of the Eastern Alborz Mountain Ranges. One of the sedimentary rock units that crops out in this area is Soltanieh Formation (Upper Precambrian Lower Cambrian). Thin section and oxygen isotope studies have been used in order to determine the petrological characteristics and the temperature of Soltanieh dolomites formation environment. Examination of the petrographic properties of the dolomite samples, along with geochemical data reveals that all of the dolomite samples are diagenetic (secondary) and were formed under reducing conditions in shallow to deep phreatic environment. The heaviest and lightest 180 values illustrate that temperature of early to late diagenetic dolomites range from 72 oC to 113.5 oC respectively.

Gold - Polymetal mineralization of Kohe-zar area is located alout 35 kilometers southwest of Torbat – Heydarieh in Khorasan province. Mineralization was occured in quartz - specularite ± pyrite ± chacopyrite veins and veinlets. The main ore minerals are specularite, chalcopyrite, pyrite, avinite (Bi - bearing tetraedrite), acanthite, native bismuth (occurred intergrowth with barite), native gold, electrum, coveline - digenite and weathered minerals such as geothite, hydrogeothite, cu-fe oxides, malachite. Ore minetalization of Kohe - zar is related to low - sulfide, quartz - hematite type of hydrothemal ore deposists. On the basis of thennobarogeochemical investigation on quartz, medium temperature fluid with low potential mineralization is responsible for mineralization in this area.

The Zonuz irregular lens shaped kaolin deposit located in Marand, Azarbaygan, is exploited as an open pit. Andesite, Trachyandesite and dacite igneous rocks are located in south, west and east parts of the deposit, respectively. The Ore was analysed by XRD, SEM and NAA. Assemblage of major minerals including Quartz, Kaolinite, Illite and Calcite, and minor minerals of Dolomite, Montmorillonite and Limonite are detected. Geochemical analysis show that La, Ce, Nd are present in minor amounts, and the high ratio of LREE/HREE indicates the enrichment of LREE which is probably the result of surface tension of these elements on clay particles. Geological and Geochemical evidence indicate tha~ hydrothermal fluids played a major role in the formation of the Ore body, particulary along fault zones. A comparison is also made between autogentic Zonuz deposit with allogentic Esteghlal deposit.

The Upper Devonian - Lower Carboniferous Sourian complex, is composed of clastic - carbonates, volcanic, metamorphic rocks and quartz lenses hosts copper mineralization in Gian area of Fars province.This complex is metamorphosed to green schist facies. This metamorphism resulted in massive to disseminated sulfide mineralization in the direction of schistosity and within quartz lenses. Low-grade green schist facies metamorphism is recognized with catalectic flow and fracturing of pyrite crystals, infilling of fractures of pyrite with chalcopyrite, pressure shadow of chalcopyrite around pyrite, recrystalization and presence of triple junctions in pyrite. Distribution pattern of REE in schists of Gian copper shows a decreasing trend from La to Lu. The ratio of ΣLREE/ΣHREE is more than one and the ratio of LaN/ YbN is less than 15. This indicates that schlsts are formed by the metamorphism of shales and the ratio of (La/Lu)cn> 1 indicates that the transfer of REE has been affected by surface adsorption. It may be concluded that this copper occurrence is the result of ore-bearing shale metamorphism.

Skarn occuring in the Sangan area was formed within two different rock roups, graitoids and skarns. Based on the new amphibole classification and nomenclature, the general formula of amphibols is (AB2C5T8O22OH)2. Amphibole of granitoids is a ferroedenite in which Si = 6.87 - 7.75, CaB> 1.5, (Na+K)A> 0.5 and Ti < 0.5. Skam amphiboles are mostly developed within amphibole skarns and gamet-pyroxene skarns during retrograde stage of skarn evolution. High-temperature amphiboles are rich in Al while low-temperature amphiboles are poor in AI. Skarn amphiboles are classified in two groups: (a) hastingsite in which Si = 5.99- 6.08,CaB> 1.5, (Na+K)A > 0.5, Ca < 0.5 and Al < Fe+3. (b), ferroactinolite in which Si = 7.61 - 7.90, CaB>1.5, (Na+K)A< 0.5 and CaA< 0.5. Amphibole in (a) is Al-rich while amphibole in (b) is Al-poor.

In this paper, MnCl2 4H2O crystals with monoclinic structure, for the study of magnetic hyperfine field in magnetic crystal at low temperature, have been grown. To study the effect of impurities on Tl (spin-lattice relaxation time), crystals with different percent of 59COimpurities, from saturated mixed solution of MnCl2 4H2O and CoCl2.6H2O at temperature of 300oK, have been grown. The percent of cobalt impurities in the solution and crystal was determined by using the radioactive isotopes of 54Mn,60CO and 57CO as probes. The result indicated that the ratio of 59Co/55Mn was about 6.2% which has a good correspondence with the results of the NMRON spectrum of 54Mn in low temperatures (T<100mK).

The use of lime as additive to soil is a very common technique in engineering projects. The purposes of this proceses are the increase in strength and a decrease in plasticity behavior of the soil. The results of this research indicate that in the chemical interaction process of soil minerals with lime, a part of minerals, specifically clay minerals, transform to other minerals. In fact, this transformation is the base for the different mechanical response of soil. In the present study, attention is made to the tri-calcium-silica- hydrate (CSH), tetra-calcium-alumna hydrate (CAH), and ettringite, as the three major minerals formed in this process. This transformation is monitored by use of scanning electron microscope and x-ray diffraction testing.