مجله بلور شناسی و کانی شناسی ایران
سال ششم شماره 2 (پیاپی 13، پاییز 1377)

The Esfordi iron - apatite ore in Central Iran is locAted in Bafq metallogenic province. Stratigraphically most of the rock units belong to Precambrian and Cambrian sequenses which the sedimentary and volcanic series are the most spreading rock types and mineralization took place just within the vOlcanic-sedimentary unit of the mentioned series. Study of REE contents of apatite in Esfordi iron-apatite orc shows high concentration of thClie elements. Zonal distribution of some REEs, e.g. La, is identified which varies from center to the rim of apatite ~ingle crystal. Absence of negative Eu anomaly makes the Esfordi apatite distinctive from the igneous types and may indicate a hydrothermal origin for Esfordi apatites. •

The EDT A gel processing route has been used to produce (2223) BSCCO superconductiong oxides. Gel - processed (2223) BSCCO material was sintered in air or oxygen to produce specimens for transition temperature determination; the same specimens were characterised by high re.chr('39')ioultion transmission electron microscopy fitted with EDAX analysis to yield information about homogeneity, microstructure and identification of any grain boundary phases that may be present. Electrical resistivity ~"rew;:."", ~~"" btel ",le "1"chr('39')tI ~" .;tIerell ",.en.s to allow the superconducting transition temperature to be determined as a function of sintering atmosphere. Transition to a superconducting state at I 10k was observed in samples sintered and quenched in air

In [his research endo-3-diphenylphosphino -(IR)(+) camphor as a ligand was synthesised. 1.3 mmol of IrC12(NCPh)2 was added to the solution of 2.7 mmolligand in 15 ml dicloromethane, and after one hour it was evaporated at reduced pressure. By addition of methanol microcrystals of yellow complex of lridium(I) with 78% yield was obtained. Crystal structure of the above complex are orthorhombic, space group P212121 with a = 380.3(2), b = 1785.1(3), c = 19.228(4)A and z =4, R = 0.0453 for 4438 observed reflections. The structure shows that PPh2 groups are endo and phosphines in cis position.

The Jalal Abad iron ore deposit is one of the seven most important iron ore deposilS in the central Iran. with a probable are reserve of 200.4 million tons of iron ore in which the average grades are estimated as 44.28% Fe, 0.83% Sand 0.07%P. In the Jalal Abad deposit two types of orebodies are identified: the orebodies which are concordant with respect to the sedimentarY most rocks (Jalal Abad I). and the orebodies which are discordant with respect to their carbonate host. rocks (Jalal Abad II). In this deposit the primary ore minerals are magnetile and hematite. Hematite is also formed from the oxidation of magnetite. It is proposed that the deposit was rormed in two stages as describled below. 1) The principal orebodies were chr('39')formed contemporaneous with the sedimentation. from the exbalites and precipitates associated with volcanic activity within an intracontinental sources. This pan of the deposit is named Jalal Abad l. 2) After formation of the Jalal Abad orebodies. due to emplacement or the igneous rocks within the ore zone, the meteoric and/or connate water contained in the Jalal Abad J:then iron was redeposited from the upwelling iron bearing solution as replace,m ent orebo<1ies within the carbonate rocks. 1n this manner JalaJ Abad II orebodies were formed.

Vein and hydrothermal . sedimeOI~ry types of magnesite from eastern Iran probably originated from ascending hydrothermal solutions. The cryptocryistalline magnesite is very pure although it has a variable CaO/Si02 ratio. It is compact with a very fine and uniform texture. The mineralogy of samples of dead burned magnesites calcined at different temperatures and times arc variable and can be predicted from phase equilibria studies. The textural relationships studied using scanning electron microscopy show that matrix is concentrated at peric1ase crystal boundaries particularly at the triple points. The periclase crr-itals are larger at increased calcination temperatures and times. The amount of periclase - Periclase grain contact reduces by increasing the amount of impurities. Electron microprobe results confirm that CaO and FeO in periclase increase steadily with the increase in the CaOlSi02 ratio and FeO content of bulk chemistry respectively. The mineral chemistry of forsterite. monticellite. merwinite, dicalcium silicate and tricalcium silicate in dead burned magnesite indicate some solid solution between some phases, although sometimes it is difficult to analyse single phases. This study indicates that high quality dead burned magnesia bricks can be produced from the Iranian natural magnesite with low CaO , Si02 and FeO impurities and by maintaining the CaOlSi02 ratio of around 2:1.

In th is work, permeabi lity variation of Ni and Ni-Zn ferrites due to microstracture is slud id. The conventional wet ceramic techniqe was used for the preparation of the sampla. The samples were shaped in the form of toroids and disks and were sintered in differant tempraturees. using a LCR-meter, inductance of loroidchr('39')i was macsured and tben pennaebility was calculated. To see the relation between grain sise and permaebility. a series of SEM photographs were obtained. The results of these photographs shows that with increasing the si ntering temperature the mean size of grans will increase. In the o ther hand, the magnetic measu rement on toroid samples show that with increasing the mean size of grain the magnetic premeability increases, bUI Ihis procedure will nOI continue and then it falls. The reason of this behavior is describe based on displacing of grain boundaries so that the porosities faU in the grains