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I would like to thank The Australasian Institute of Mining and Metallurgy for inviting us to share with you some of our experiences in the handling, storage, and transportation of industrial minerals in North America. Cometals, Inc. is a wholly-owned subsidiary of Commercial Metals Company, headquartered in Dallas, a public corporation whose shares are traded on the New York Stock Exchange. Sales exceed one billion dollars. Cometals, Inc. is located in New York and specializes in marketing of chemicals as well as raw materials used in the manufacture of steel, refractories, abrasives, glass and ceramics. This makes us one of the larger regular shippers of industrial minerals. Many people are aware that industrial minerals need to be viewed and judged on the merits of their chemical and physical characteristics. In addition you are surely aware that close attention must be paid to the economics of these minerals to determine the appropriate value and competitiveness of the minerals or products delivered at the doorsteps of the consuming work. You may, however, not be aware that the handling and transportation of the mineral is of crucial importance, in fact, the transportation and handling costs of industrial minerals frequently are a major component of the value of the ores marketed and, therefore, it is only natural that close attention should be paid to them. Many of the industrial minerals require special handling to assure that the material reaches the consumer without being contaminated and without getting wet. I invite you to accompany me through the various steps involved in "delivering the goods" to the consumer.

Jan 1, 1989

How the Australasian and Canadian Codes (VALMIN and CIMVal) approach mineral property valuation is described. Brief comment is also made on the International Valuation Standards CommitteeÆs interest in a global valuation standard for Mineral (Extractive) Industries and the South African SAMREC initiatives to adopt a VALMIN-like Code. The conventional tripartite classification of valuation approaches into those that are Market-based, Income-based and Cost-based is outlined. It is best practice to use as many of these approaches as possible (and as many methods as reasonable in the particular circumstances), given the quantity and quality of the data available on the Mineral Asset (which depends upon the state of development of the mineral property). The use of specific methods must satisfy the basic considerations of logic and reasonableness and the purpose of the valuation. The competence, judgement and repute of the valuer are critical factors, since all valuations are time and circumstance specific. What constitutes æMarket ValueÆ in the different jurisdictions is discussed and definitions are given. Challenges facing the globalisation of a VALMIN-type Code for the international Minerals Industry are the influence of real estate valuers and the US jurisdictional idiosyncrasies. This is mainly due to a fixation on real property rights with a preference for using real estate-like comparative sales techniques (Market Approach) to the exclusion of Income-based approaches; a regulatory reluctance in the US to accept that Resources have considerable value; and the International Accounting Standards BoardÆs preference for Historical, rather than Current Value, accounting.

Jan 1, 2002

By D Reid, A Fourie

The in-pipe treatment of slurries with polymer addition shortly prior to deposition is a noteworthy emerging technology of increasing popularity. Although polymer treatment has been shown to substantially modify and improve depositional and dewatering behaviour in a significant number of cases, the impacts of polymer treatment on geotechnical performance of tailings are less well understood. For example, certain combinations of polymer and slurry type have been shown to result in lower final densities at a given vertical effective stress. Despite these lower densities, polymer-treated tailings often exhibit peak undrained shear strengths consistent with untreated material. However, the sensitivity and/or brittleness of the material may be negatively influenced by the looser state created. Although these changes have been studied, most testing available in the literature was undertaken on relatively ‘fresh’ samples of polymer-treated material. However, significant shear may occur following treatment and prior to the commencement of settling and self-weight consolidation as the material moves down the beach.To study the effects of shearing on the subsequent performance of polymer-treated tailings, a test program consisting of consolidation, triaxial and direct simple shear tests was undertaken on presheared polymer-treated material. Materials used were identical to those used in previously published studies on the impacts of polymer treatment in a ‘fresh’ condition. Shearing of the polymer-treated material generally appeared to lessen the impacts of the polymer treatment process. However, the behaviour of the material when sheared indicated that the polymer was still impacting the behaviour of the material in some respects. The results indicate the importance of the consideration of shearing on material behaviour when planning and designing a tailings deposit where polymer treatment is to be implemented.CITATION:Reid, D and Fourie, A, 2015. Effects of shear on the behaviour of polymer-treated slurries, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 215–224 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

The extractive industry has been faced with a situation where there has been no systematic and formalised training and education structure available. Previous structures which were available, e.g. the quarrying diploma and the mining papers as a part of an engineering degree, have suffered the same fate as the Dodo. They are now extinct.   In providing for a training strategy, the past strategies need to be examined and reasons behind their demise examined. This paper examines the reasons for past failures in education and training in the extractives industry, the factors that need to be taken into account in creating an education and training culture, the strategies required, the Government regulations and trans-Tasman agreements, and the quality management which must surround the entire training programme.

Jan 1, 1997

The Hyde Macraes Shear Zone (HMSZ) is an extensive low angle semibrittle mineralised structure in the Otago Schist Belt, New Zealand. The shear zone is located on the lower limb of a late metamorphic recumbent fold. Structural observations suggests that the shear zone initiated as a high strain mylonite zone and transgressed the ductile/brittle boundary (D4) later in its development. A surge zone at Round Hill is bounded to the south by a NE-SW striking lateral ramp which displaces the hanging wall shear (HWS) by 50 m. Oblique strike slip displacement during surge zone propagation created space for deposition of the sheeted vein complex or stockwork. Quartz recrystallisation in stockwork veins suggests that the veins were deformed in a ductile manner and implies that surge zone propagation may have occurred during late D3 deformation. A macroantiform was produced during D3/D4 shortening below the HWS. Over tightening of the antiform hinge created SW and NE-dipping ramp thrusts. Continued strike slip displacement along the lateral ramp rotated the antiform and associated ramps into a south plunging drag fold. Post-mineralisation (D5) structures include NE-dipping nonna! faults below the HWS and SW-dipping low angle imbricate thrusts above the HWS. The development of these structures was kinematically compatible with normal movement on the HMSZ and is related to mid Cretaceous break up of Gondwanaland in the SW Pacific.

Jan 1, 1992

By R P. Varden

This paper looks at the design of the Bentayga raisebore with subsequent back analysis using a LiDAR survey. A search for LiDAR raisebore assessment publications shows little work has been done on this subject. The paper examines the empirical design and RS2 modelling assessment with the bored condition. The high resolution of the LiDAR enabled mapping of weak structures that were located on the geotechnical investigation hole the orientations of which could not be determined. In addition, the scan showed were water ingress was occurring, potential stress overbreak and structural controls on stability. The LiDAR results were able to confirm no additional support work such as a shotcrete liner is necessary. The LiDAR results have been analysed in one metre increments as volume of overbreak against the empirical stability criteria (McCracken & Stacey 1989). The future use of LiDAR mapping over a range of rock mass conditions will provide quantification of the established empirical assessment improving its reliability. It is also a useful and accurate tool to monitor long term stability of a raisebore due to stress change or ore pass due to wear.

Mar 15, 2021

By L Dixon, J Carter, K Auyong

Fourier transform infrared (FTIR) spectroscopy and other near infrared (NIR) tools have been used in the bauxite industry for many years. Infrared spectroscopy exploits the differences in chemical composition and lattice structure to produce a characteristic response. Spectral devices, such as those from ASD Inc and the HyLoggerTM, provide qualitative mineralogical data targeted towards hydrated minerals detected in the near and short wave infrared region. The FTIR spectrum extends into the mid and thermal infrared range and can therefore respond to the presence of silicates and oxides, in addition to hydrates and carbonates.The key to successful utilisation of infrared spectra, however, is the interpretation methodology. In this study, FTIR spectra were calibrated against quantitative X-ray diffraction data for the determination of the mineralogy of iron ore. A full pattern profiling machine learning technique was utilised for the calibration, and the assessment of the regressions determined from an independent validation set. The abundance of key minerals – hematite, goethite, kaolinite and quartz – were determined and the results correlated against X-ray fluorescence assays and loss on ignition data. The results of the study indicate that spectral techniques using a full-pattern profiling machine learning approach and artificial neural networks can be used successfully to obtain objective and quantitative mineralogical data to support field observations and analytical results for iron ore resource modelling. A comparison of this technique to the cost, quality and timeliness of other quantitative mineralogy tools is also made.CITATION:Carter, J, Auyong, K and Dixon, L, 2017. Determination of iron ore mineralogy using Fourier transform infrared spectroscopy and machine learning, in Proceedings Iron Ore 2017, pp 519–528 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By M Bird, B Oats, M Sganzerla

Mining operations are continually aiming to reduce operating costs to improve plant profitability. One way in which the Cannington operation sought to achieve this was by increasing the wear life and reducing the energy consumption of their flotation mechanisms. This was made possible using Outotec’s FloatForce mechanism. The FloatForce mechanism has been developed by Outotec over a six year period involving both CFD modelling and rigorous site testing. FloatForce delivers improved air dispersion and cell agitation efficiency; as such it can be operated at lower rotor tip speeds when compared to Outotec’s previous mechanism.Cannington trialled three FloatForce mechanisms in a train of ten OK38 zinc roughers. The mechanisms’ rotational speed was reduced by 10% compared to the previously installed MultiMix mechanisms. The purpose of the trial was to quantify the energy saving and assess whether there was any reduction in plant metallurgical performance.The trial was successful with FloatForce delivering a 17% reduction in power, an improvement in wear and improved recovery. Analysis of pre and post-installation metallurgical accounting data showed the following:The FloatForce installation resulted in a recovery increase of zinc to zinc final concentrate of 0.4 – 4.0%*The FloatForce installation resulted in a recovery increase of lead to zinc final concentrate of 0.0 – 0.3%*There was no statistically significant change in silver recovery to zinc final concentrate that can be attributed to FloatForce**95% confidence interval (CI) using multiple linear regression models.The Cannington operation is now in the process of further optimizing its power consumption and wear savings by changing the remaining OK38 zinc and lead rougher float cells to FloatForce mechanisms.CITATION:Bird, M, Oats, B and Sganzerla, M, 2015. Improvements in flotation cell maintenance, power consumption and operation at South32 Cannington, in Proceedings MetPlant 2015, pp 230–245 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

Radioisotope x-ray and neutron techniques of analysis can be used for the determination of a wide range of elements in minerals. The most important applications of these techniques to the mineral industry are for onstream analysis of slurries and solids, and for geological assay.The radioisotope x-ray techniques are the more developed ones and two installations for on-stream analysis are in routine use in mineral processing plants in Australia. Neutron techniques are being developed, and should prove valuable for geological assay of large numbers of mineral samples, for borehole logging, and for specific on-stream analysis when the cost of the equipment is warranted.

Jan 1, 1970

By E Westthorp

Final mine sealing of BMA’s Crinum North mine, near Emerald, Queensland was undertaken in December 2015. Due to the benign atmospheric environment at Crinum North, the Queensland Mines Rescue Service (QMRS) Górniczy Agregat Gasniczy (GAG) unit was utilised to reduce oxygen levels throughout the underground atmosphere as part of the final sealing process.The GAG was utilised by way of a vertical borehole from the surface to seam to successfully reduce oxygen levels throughout the underground mine workings. Application of the GAG unit enabled the underground mine to be classified as stable and inert within days of the GAG operation, and subsequently cease gas monitoring at Crinum North. The data and information obtained from this activity provides valuable information to the underground coal mining industry on successful application of the GAG in realistic situations.This paper discusses the strategy used for sealing, the assisted inertisation and the results obtained from the application of the GAG unit. It discusses both the overall results and gives a detailed review of the gas monitoring data obtained via the tube bundle and real-time system, both during and following the use of the GAG unit.Gas monitoring results obtained and the strategy used are critical to share with the industry to obtain a better understanding of how the GAG unit works, and how it can be applied for emergency preparedness, emergency response or planned inertisation.CITATION:Westthorp, E, 2017. A review of the strategy and gas monitoring results obtained during the use of Queensland Mines Rescue Service GAG unit at Crinum North mine, in Proceedings Australian Mine Vent Conference 2017, pp 309–318 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

At its Port Kembla Plant, Australian Fertilizers Ltd. manufactures Superphosphate and other Phosphatic Fertilizers.Phosphate Rock is received from Nauru and Ocean Island. It contains water insoluble tri-calcium phosphate, Ca3(PO4), to an average of about 86%.It is crushed to pass a 20-mesh x 26-gauge woven wire screen, and is then treated with Sulphuric Acid to give the product Superphosphate with a water solubie prosphate content of 20.5%, estimated as P205. Sulphuric Acid is made by the chamber process. Three sets of chambers are installed, on,e five-chamber set of timber frame work construction and the other two of more recent date, each with four chambers of steel frame work construction. A fourth chamber set is now being built.Sulphuric Acid is delivered for use. at about 70% H2S04, the strength depending upon the rock used.Mixing - The crushed rock and sulphuric acid are mixed in weighed and measured proportions respectiyely in one-ton batches in revolving cast fron pans, mechanically stirred. The mixture, while still slurry, is run into a closed horizontal concrete cylinder (den) where, with the completion of the chemical reaction, it rapidly sets as Superphosphate.Approximately fifty batches are required to fill a den. When full, the den is opened ana the mass cut out by a revolving cutter. The product is elevated and conveyed to any required position in the Superphosphate storage shed, where it dries and matures.Despatch - As required, the Superphosphate is excavated by a two ton grab and conveyed from the matured "dump" to bagging units where it is disintegrated, screened and bagged at twelve bags to the ton. The filled !Jags are closed by machine and delivered to railway trucks immediately.Mixed Fertilizers - Sulphate of Ammonia, Sulphate and Muriate, of Potash, and Blood and Bone are mixed with Superphosphate and thoroughly incorporated to give different mixtures to meet special plant requirements.

Jan 1, 1938

By J Seppelt, B Akerstrom, J Bubnich, D Seaman, T Waters

The Cadia Hill concentrator at Newcrest’s Cadia Operations has undergone several modifications and upgrades to treat an increased throughput rate of harder ore from the Cadia East block cave mine.Subsequent to the commissioning of the expanded circuit, the flotation cleaner block has undergone a systematic optimisation programme tackling all facets of circuit operation. This included debottlenecking circuit constraints and installation of Jameson cell technology to enhance copper and gold recovery while rejecting fluorine and gangue from the concentrate.This paper outlines the improvements over the course of the project and results obtained from the implemented actions.CITATION:Akerstrom, B, Seppelt, J, Waters, T, Bubnich, J and Seaman, D, 2018. Cleaner circuit optimisation at Cadia Operations, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 457–476 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By T Howard, J E. Everett

BHP Billiton Iron Ore has replaced the conventional product quality control batch system at Yandi with the Continuous Stockpile Management System (CSMS) centred on a fully integrated æcontinuousÆ stockpile flow from mine planning through to port reclaiming. With increasing tonnage rates, tight operational coupling associated with the original batch system caused production interference which achieved final product quality but in an increasingly inefficient manner. This innovative approach places a continuous emphasis on product grade control and takes full advantage of the most appropriate blending opportunities of the mine to port planning and production system in order to reduce the natural variability of the ore to an acceptable level. To implement continuous control, product variability throughout the process is classified as long-term and short-term. Long-term variability is best controlled through the monthly mine planning process which determines monthly grade targets while taking into account optimum mine development. In the past, attempts to control long-term variability were made at the port through selective stockpiling and reclaiming which reduced operational efficiency. Short-term variability is best controlled around the monthly mine grade target by daily mine production scheduling, train sequencing, stacking into port stockpiles of appropriate size and systematical stockpile reclaiming. The implementation of the new system has maintained customer accepted shipping grades and has provided significant improvements in resource utilisation, operational efficiencies and costs.

Jan 1, 2002

By C E. Vidal

Geological exploration and mining development increased their intensity and rate of success during the last five years in Peru. Particularly relevant are the mining projects of Yanacocha and Pierina for epithermal Au and Ag. Also relevant are the new mining operations at Iscaycruz and Uchucchacua for limestone replacement Zn- or Ag-rich base metal skarn deposits. Miocene continental volcanics host the low-grade but near-surface orebodies of the Yanacocha mining district in Cajamarca. Several deposits have been mined since 1994 with open-pit and heap-leach gold production increasing from 300 000 ounces to 1 300 000 ounces in 1998. In a similar geological setting, but with three times the grade of Yanacocha, the Pierina valley-leach operation in Ancash is set to produce 800 000 ounces Au during 1999. At Iscaycruz in Lima, Cretaceous limestones host massive pyrite and sphalerite skarn deposits with 10 to 20 per cent Zn. Mining and milling were started in 1996 with last yearÆs production rising to 180 000 tonnes of Zn concentrates. At Uchucchacua, selective underground mining of fracture-controlled Ag skarns, with 400 to 420 g/t, has been recently increased from 1200 to 2000 tonnes per day to produce 5.5 million ounces Ag during 1998. Advanced exploration projects are located in the framework of nine Phanerozoic metallogenic provinces. Mineral deposits of preferred attention are precious metal disseminations and veins, base metal replacements and skarns, porphyry Cu (Mo-Au), Mississippi-Valley-type Zn and base metal volcanogenic massive sulphide deposits. Geological discovery of new orebodies enables a sustainable development of the mining industry in the country.

Jan 1, 1999

By H Arvidson, C Morley

Reconciliation has become very topical over the last ten years but how do we distinguish what is good practice, and even more importantly, show how it adds value? Reconciliation at Anglo American has received support from the very top of the company and this has enabled success in the design and implementation of a range of processes, reporting activities and actions. Focus has been on full Mine Value Chain Reconciliation (MVCR) from Resource to Product and on proactive cross-functional engagement. A standardised set of reconciliation definitions and relationships are used at all mines across the company to diagnose planning and performance issues. Results are formally presented in an efficient dashboard format, accompanied by a concise narrative to communicate what has been learned and what is being done to correct, improve or change practices. Importantly, effort has also been made to sustain MVCR by embedding good practice and quantifying the benefit of reconciliation explicitly via linking results to value.This paper sets out the lessons learned from the past two-years’ journey, highlighting areas where good practice has been defined and achieved. A ranking for quantifying reconciliation confidence over time is presented as a means of putting results into context and continuously improving the reconciliation process. Finally, a solution to define the value that can be derived from reconciliation is described, detailing how cross-functional personnel meet monthly to review results and implement actions that are tracked in terms of value creation.CITATION:Morley, C and Arvidson, H, 2017. Mine value chain reconciliation – demonstrating value through best practice, in Proceedings Tenth International Mining Geology Conference 2017, pp 103–116 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

The Kalgoorlie Golden Mile is proposed as an Archaean volcanogenic-type deposit, modified and redistributed along later-developed structures. Rich pyritctelluride and Green Leader gold mineralization is associated with the end phase of basic volcanism and, in a general sense, is confined to a broad interface zone between the products of marine basic volcanism and later acid volcanism. There is virtualIy no ore associated with the main body of acid volcanics.Green Leader is the local name of a type of ore that occurs at some igneous rock contacts in association with graphitic sediments and layered acidic tuffs. It is characteristicalIy green, of various shades, and commonly yields very high gold assays, the reasons for which are not apparent in hand specimen.Carbonates, carbonaceous shales, tuffites, rich gold ores, and acid and intermediate dykes, alI indicating a common heritage, are features common to the main ore hosts, viz. the Paringa Basalt (Calc Schist) and theGolden Mile Dolerite ("Quartz Dolerite Greenstone").Several probably related fracture systems have reconstituted most, but not all, of the original deposits into a large number of steep tabular lodes.Includes two sets of discussions and comments from later Proceedings volumes.

Jan 1, 1974

Alluvial gold mining in New Zealand and in particular on the West Coast underwent a renaissance during the early 1980's. This was based on two main factors: a) the sharp rise in the gold price b) the advent of the hydraulic excavator with which to mine the auriferous gravels. The scale of operations varies considerably. A small operation typically consisting of one or two people using an excavator to feed either a land based or pontoon mounted (floating) gold recovery unit, which will typically feature a rotary screen with or without a tailings stacker with the screened fines < 10 - 15 mm) fed over riflle tables. The largest screening plants of this type are operated by DML Resources in their Arahura and Mikonui mining operations where the plants have the capacity to screen up to 250 m3 of gravel per hour. These plants usually employ jigs and centrifugal concentrators for gold recovery. Unique amongst current operations is the Grey River Dredge, a bucket ladder dredge capable of processing 700 m3 per hour similar to those that operated earlier this century. Gold concentration is by a series of jigs. The number of plants operating in recent times peaked at around 130 in 1987 (coinciding with a nominal average gold price of $751) and since that time has steadily declined to 80 units in 1993 and about 45 - 50 units today. This cycle of rapid expansion and then steady decline has been repeated on the West Coast since the original gold discoveries in the mid nineteenth century.

Jan 1, 1996

By S Thomson, M Lovitt, T Purvis, C te Kloot, T Nguyen, Z Liu

Ernest Henry Mine (EHM), located in north-western Queensland, is an underground copper/gold sublevel caving operation currently producing over 6 Mt/a of ore. The mass mining method of sublevel caving (SLC) used at EHM involves systematically blasting a series of uphole rings in parallel ore drives and drawing the broken ore using a top-down approach. Each ore drive contains multiple precharged rings to prevent having to charge in close proximity to the brow of the previously fired ring; however, the current initiation system still involves ‘hooking up’ all detonator lead cords of the first precharged ring. The unstable nature of a rill and working close to a brow presents hazards to personnel completing the hook-up process. There is also a business risk of ore loss when damaged ground support completely prevents access to the next precharged ring. If the hook-up step could be eliminated, the risk to personnel and the business would be significantly reduced.EHM engaged Orica Mining Services in 2016 to trial their WebGenTM 100 – wireless electronic blasting system (WEBSTM) for the first time in an underground mining environment. Having successfully signal-tested the equipment, two test holes were initiated, followed by a single production ring and then multiple production rings. In total, 30 production rings were successfully fired underground at EHM in 2017. To do this, WEBSTM was successfully integrated into EHM’s current charging and firing process, resulting in no business delays or loss to production. None of the 30 rings required hooking up and all were initiated from the surface with no personnel underground. A high level of ownership from all personnel involved ensured the trial was a success, and provided scope for wireless detonators to be used successfully on a large scale – both at EHM and other sublevel caving operations. WEBSTM is now a proven example of technology that can be used to improve safety in the mining industry, through eliminating the need for personnel to work in hazardous areas.CITATION:te Kloot, C, Liu, Z, Purvis, T, Thomson, S, Lovitt, M and Nguyen, T, 2017. Improving safety through technology – Orica wireless electronic blasting system trials at Ernest Henry Mine, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 39–50 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By B Xiao, J Yang, H Chen

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Tuwu-Yandong Cu deposit, located in the East Tianshan mountains in the eastern section of the Central Asian Orogenic Belt, is the largest and economically most important porphyry Cu deposit in Xinjiang, China. It contains ~3 Mt of copper at an average grade of 0.46 per cent Cu and 0.2 g/t Au, with significant amounts of Mo and Ag. The deposit is mainly hosted in the Carboniferous Qi’eshan Group and plagiogranite porphyry, and is controlled by faults that are east–west-, north-west- and north-east-trending. Ore minerals in the Tuwu-Yandong deposit are dominated by pyrite, chalcopyrite and molybdenite, with minor bornite, chalcocite, magnetite, sphalerite and galena. Gangue minerals are mainly composed of quartz, sericite, chlorite, epidote, anhydrite, gypsum, muscovite, biotite, phosphorite, sphene, dolomite, actinolite, barite, albite and calcite. Based on the megascopic and microscopic textural relationships and mineral assemblages, five stages of hydrothermal alteration and hypogene mineralisation are recognized in the Tuwu-Yandong Cu deposit: the potassic stage, propylitic stage, phyllic stage, late veins stage and supergene stage. Most of the copper was deposited during the phyllic stage, along with less molybdenite.CITATION:Xiao, B, Chen, H, Wang, Y and Yang, J, 2015. Geology, mineralisation and alteration of the Tuwu-Yandong porphyry Cu deposit, north-west China, in Proceedings PACRIM 2015 Congress, pp 641–644 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

The latest outcome of science is that aII bodies are composed of vibrating atoms or molecules. In almost all mineral bodies when changing from the gaseous or liquid condition to the solid, if the vibrating molecules are allowed free play, they arrange themselves in a symmetrical manner, and at a definite angle to each other: This angle varies with each system of crystallization. In a great many bodies this process may be brought about artificially, and the growth of the crystal watched. The most common method is to dissolve some substance in water or some other liquid, on slowly evaporating the liquid, the substance dissolved will solidify and the molecules will arrange themselves in their particular crystalline form.The element carbon crystallizes in two forms; as graphite in the form of a short six-sided prism', and in the diamond generally as the octohedron in the cubical system of crystallization. Orystalline bodies, as a rule, have plain faces but what is remarkable in the diamond is that in a great many cases the faces are rounded. Its great beauty as a gem when cut, and the high artificial value placed upon it by fashion, as well as its value as a cutting and boring instrument-it being the hardest body in nature-has caused many attempts to be made to form it artificially. These attempts have met with fair success as a scientific experiment, but as a commercial speculation they have been a complete failure. The most noted of these experIments was carried out by Mr. Hannay, of Glasgow.Paraffin spirit with lithium was submitted td prolonged heating in strong wrought-iron tubes securely welded. In most of the experiments the tubes exploded; but in a few cases the experiments were successful, and on cutting open the tubes small crystals of diamonds were found embedded in a black mass.Despretz produced minute diamonds under the influence of a powerful electric current from coal.