Journal of Gems And Precious Metals
Volume:1 Issue: 1, Spring 2021

At the end of 2014, around the so-called Loxtondal Orangeitic (now called Kaapval-type lamproites) cluster, in Boshof district, two circular anomalies (~540 to ~1100 meters in diameter) were identified by Landsat Satellite Images and interpreted as being of "kimberlites" pipes; probable anomaly which were referred to as Olie -1 and Olie-2. Subsequently, 100 kg of soil samples (horizon A/B) were taken for each of these anomalies. From them there was a high concentration of indicator minerals (IM): olivine, garnets (violets, reds and oranges), chromites, ilmenites, rutile, frosting tourmaline, zircon and among them some crystals of micro and macro diamonds. The high concentration of IM on Olie-2 led to focus the work on it. IM of Olie-2 was burned in HFl and by caustic fusion what contributed about 86 macro (

In recent decades, mineralogy has improved rapidly; many new mineral phases known by advance analytical methods which bring several scientific mineralogical and gemological names in to use. Variously, a large number of traditional names are used in gem trades every day. Application of recently developed scientific mineralogical findings in modern gem business demand proper terminology. In this article the general mineralogy of the Persian turquoise is brought forward in order to offer a novel name.

The Sanandaj-Sirjan Zone (SSZ) is the metamorphic-magmatic core of Zagros Orogen in Iran. The SSZ has produced several styles of gold deposits during the Phanerozoic eon. The Saqez–Sardasht zone includes a NE-trending goldfield belt, located at the northern SSZ. This area, embodying the main orogenic gold deposits (e. g. Qolqoleh, Kervian, Qabaqhlujeh, Hamzeh Gharanain, Mirgeh Naghshineh) was chosen for this research in order to study the relationship between deformation phases and gold-accompanying minerals in a microscopic scale. It is demonstrated that the study area has experienced 2 ductile phases, 1 semi-ductile phase and 1 brittle phase of deformation, each associated with the shear zone progression. Gold mineralization via each deformation phase is relevant with the precipitation of new pyrites and shearing/rotating of old pyrites.

BET method is based on the absorption of some specific molecular species in a gaseous state based on their surface. This method is used to measure physical absorption which can be used for analyzing the structure of porous materials. BET data show the geometrical shape of porosity, absorption and porosity type, volume, and size of specific surface area. The instrumental methods show that the exact contents of fluids (gas or liquid) can be absorbed by the porous material surface, at different pressures, in different materials such as gemstones. BET method is used to measure physical absorption and analyzing the structure of low-grade Neyshabour turquoise as a base for their chemical treatment. The low-grade turquoises were deposited as gangue for centuries in the area. The treatment of low-grade turquoise provides a good economic opportunity to upgrade the gemological industry in the area. This research would provide a useful framework for further steps such as finding the best turquoise for treatment as well as identifying treated samples from other turquoise sources. The result of the analysis in this research shows that the geometrical shape of porosity is two sided and from an open cylindrical type. The porosity is mainly micro-pore type (p 0≤ 0.5) and the  absorption grade as high type. As a result, liquids could penetrate the low-grade turquoise rock pieces and make it possible to consider the low-grade types for further chemical treatment studies.

Hormuz salt dome (Hormuz Island) is one of the right places for the crystallization of gem minerals, where idiomorphic apatite crystals have been formed under a hydrothermal condition. This island is located in the northern area of the Persian Gulf, south of Iran. The Hormuz Island is composed of salt, anhydrite, sandstone-siltstone, dolomite, limestone, and volcanic horizons. In this research, the Hormuz apatite is assessed in terms of gem potential and mineralogical characteristics. The apatite crystals are formed 2-3 cm in size, mostly transparent and yellow to green, which indicate their gem quality. Considering thermal sensitivity and the moderate hardness of this mineral, the best methods and tools for cutting were selected through multiple testing methods. According to our research, the best approach to a fantasy or cabochon cut is the use of a 0.3 mm thin edge, 220 or 240 grit sanding discs, a 400 grit abrasive for scratch removing and 800, 1200 and 2500 grit abrasives for polishing. Respectively, use of water in all stages of sawing, cutting and polishing is necessary.

In this study, irradiation treatment was examined on colorless and clear quartz crystals collected from east of Qazvin (EQ) and southwest of Astane (SWA) regions in Iran. EQ crystals up to 3 cm were found in the geodes in andesite and trachyandesite, while idiomorphic crystals up to 2 cm from SWA formed in cavities and vugs in rhyodacitic host rocks. Crystals of both locations were exposed to gamma rays under the same conditions in steps of 100 kGy, 200 kGy and 300 kGy. No specific color change was observed for EQ crystals, while colorless SWA samples completely turned into dark gray or smoky gray from 100 kGy onwards. Comparing chemical analysis (ICP_MS) of samples revealed that SWA crystals contain more impurities with significantly higher Al. Representative Al contents in EQ and SWA samples are 322 ppm and 3378 ppm respectively. Data from Raman and infrared spectroscopy structural analyses, show similarities between studied samples from both regions. Formation of smoky quartz after radiation is related to color center defects. Field evidence reveal the direct effect of hydrothermal fluids and vapors related to Astane granitic intrusions on country rocks in the aureole, in forming colorless quartz crystals with high concentrations of aluminum impurities substituting Si.