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By Carlos Maurício F. Vieira, Lázaro A. Pizatto, Marcus Paulo Cardoso, Sergio Neves Monteiro, Joao Victor C. Nunes, Gustavo S. R. Matheus, Frederico M. Margem

The interest in composites with natural fibers is due, among other factors, to the growing worldwide concern with the preservation of environment and renewable raw materials. The natural fibers have many particular properties that make them an attractive alternative to traditional synthetic fibers. The advantages of using these fibers are: low cost, renewability, biodegradability, low toxicity, abundance and specific strength. The searching for new suitable, economically viable and technologically advanced materials justifies the accomplishment of this work that aims at comparing the mechanical behavior of polyester matrix composites with epoxy matrix composites reinforced with hemp fibers Izod impact tested. The specimens with dimensions: 10 63 12.7 mm, made in different volume fractions of fiber: 0–30 vol%. The samples were tested at PANTEC pendulum model XC-50 located at LAMAV/UENF. With this research was possible to analyse the mechanical properties of these two new materials.

Mar 1, 2018

By Fernanda de Paula, Lázaro A. Rohen, Sérgio N. Monteiro, Rafael G. de Castro, Carlos Maurício. F. V, Maycon A. Gomes, Frederico M. Margem, Anna C. C. Neves

Synthetic fiber has been gradually replaced by natural fiber, such as lignocellulosic fiber. In comparison with synthetic fiber, natural fiber has shown economic and environmental advantages. The natural fiber presents interfacial characteristics with polymeric matrices that favor a high impact energy absorption by the composite structure. However, until now little has been evaluated about the hemp fiber incorporated in polymeric matrices. This study has the purpose of evaluate the impact resistance of this kind of epoxy matrix composite reinforced with different percentages of hemp fibers. The impact resistance has substantially increased the relative amount of hemp fiber incorporated as reinforcement in the composite. This performance was associated with the difficulty of rupture imposed by the fibers resulting from the interaction of hemp fiber / epoxy matrix that helps absorb the impact energy.

Jan 1, 2015

By Ygor Macabu de Moraes, Jean Igor Margem, Carolina Gomes Dias Ribeiro, Frederico Muylaert Margem, Sergio Neves Monteiro, João Batista Vasconcelos

A natural fiber presents interfacial characteristics with polymeric matrices that favor a high impact energy absorption by the composite structure. The objective of this work was then to assess the Izod impact resistance of polymeric composites reinforced with one or two layers of batt malva and jute fibers. The results showed are markable increase in the notch toughness with increasing layers of mauve blankets and jute.This can be attributed to a preferential debonding of the fiber/matrix interface, which contributes to an elevated absorbed energy.

Mar 1, 2017

By Maycon de Almeida Gomes

Fiber reinforced polymeric composites have received widespread attention in the past four decades because of their high specific strength and modulus. In particular, research works have disclosed the potential advantages associated with the use of lignocellulosic fibers as the reinforcing phase in polymer composites (2-3). Among various natural fibers, pineapple leaf fibers exhibit excellent mechanical properties. The main chemical constituents of pineapple fibers are cellulose (70–82%), lignin (5- 12%) and ash (1.1%). The superior mechanical properties of pineapple leaf fibers are associated with their high cellulose content (6). This work aims to make the analysis of the Izod impact energy against volume fraction of palf fibers of epoxy composites reinforced with PALF. The fibers were incorporated into the epoxy matrix with volume fraction from 0 to 30%. After fracture the specimens were macro photograph analyzed.

Aug 16, 2017

By Maria Carolina Andrade Teles

Uma fibra natural apresenta características interfaciais com matrizes poliméricas que favorecem a absorção de alta energia de impacto da estrutura compósita . Este trabalho procura avaliar a resistência ao impacto deste tipo de matriz de poliéster com reforço de fibras naturais. As fibras de Fique foram misturadas com resina de poliéster sob pressão em um molde metálico, e curada à temperatura ambiente durante 24 horas . Amostras padrões foram preparadas até 30% em volume de fibras Fique alinhadas ao longo de todo o seu comprimento, estas amostras foram então testadas com ensaio de impacto Izod do pêndulo e as superfícies de fratura examinadas por microscopia eletrônica de varredura, MEV. A resistência ao impacto aumenta substancialmente com a quantidade relativa de fibra de Fique como reforço do compósito . Isto pode ser atribuído a uma descolagem preferencial da interface fibra / matriz , o que contribui para uma elevada energia absorvida.

Aug 17, 2017

By Carlos Maurício F. Vieira, Giulio R. Altoé, Maria Carolina A. Teles, Sergio N. Monteiro, Maycon A. Gomes, Frederico M. Margem, Gabriel O. Glória

Due to growing concern about the ambient impacts, the society is demanding for materials that are environmentally friendly. The lignocellulosic fibers, like PALF fibers, appears like an option to replace the synthetic ones in composites with polimerics matrices. Besides the environmental advantages, the lignocellulosic fibers have economical and some properties advantages like the low density in comparison with the synthetic fibers. Nowadays the lignocellulosic are used in industries, like the automobile and aerospace. This objective of this study was to analyze the absorbed impact energy of the composites reinforced with PALF fibers. The fibers were incorporated into the polyester matrix with volume fraction from 0 to 30%. The results showed increase in the absorbed impact energy with the increase of the percentage of fiber incorporated. The fracture surface of the specimens were analyzed by SEM (scanning eléctron microscope) and indicates that the PALF fibers act as reinforcement for the polyester matrix.

Mar 1, 2017

By H. Hejny

Economy needs mineral raw materials in almost each sector of modern life. They can only be provided by mining activities. An increasing share of the total mining production will be by underground mining. The mineral deposits will be found at gradually greater depths, including all problems associated with them. It involves an increase in overburden pressure with subsequent rock stability problems and risks of structural collapse. There is a need for new and safe technologies for almost all parts of a modern mine. The mining industry faces a number of challenges which require technical solutions that encompass the entire network and include the economic, social and environmental issues. The industry needs a new image based on pioneering solutions and a modern structure that can exploit minerals at greater depths and promote both high productivity and safe working conditions. Funding has been secured from the European Commission for the I²Mine project. Work started in November, 2011. This initiative is designed to focus on the technological challenges that the mining industry is currently facing including the exploitation of ever deeper deposits and the aspiration for an invisible, safe, zero impact mine. The project comprises a consortium of 27 organisations from 10 European countries. I²Mine marks the start of a series of development activities aimed at realising the concept of an invisible, zero impact, deep mine. The extractive sector, still seen as being old fashioned and environmentally unfriendly, will show that mineral extraction and processing can be done in a highly innovative and sustainable manner with low impact underground and zero impact above ground. The concept of I²Mine is to develop innovative methods, technologies, machines and equipment necessary for the efficient exploitation of minerals and disposal of waste, all of which will be carried out underground. This will dramatically reduce the volume of surface transportation of both minerals and waste, minimising above ground installations and reducing the environmental impact. New eco-efficient technologies will be applied in order to make the entire mining process more efficient and environmentally sound. The concept is for an integrated mine, with the majority of the installations underground, and only the final product will be transported above ground to be shipped to the customer. Production waste will be treated and stored underground and gaseous emissions will be managed underground as far as practical. I²Mine will also focus on ideas and concepts that increase energy efficiency and decrease waste. The core of the project will be to develop breakthrough technologies for autonomous, highly selective, continuous mineral extraction processes and machinery based on new sensor technologies, face front separation as well as innovative concepts for mass flow management and transportation integrating state of the art technologies. The concept of an invisible, zero impact mine requires a refined process underground that selectively extracts the mineral thereby reducing waste. For this reason, improved extraction machines and near to face processing methods, including backfill procedures, need to be developed. These developments include rock mechanics and ground control solutions, incorporating health, safety and environmental issues.

Aug 1, 2013

By Siyabonga Malevu

Chemical Initiatives? Umbogintwini plant is the production facility of Chemical Initiatives? business. Umbogintwini?s J Plant manufactures sulphuric acid. The plant was designed and built by Simon Carves, and was commissioned in 1974. The plant was designed to produce 500 tons/day of Sulphuric acid (H2SO4) at maximum rates. The Sulphuric acid manufacturing is through the famous contact process whereby liquid Sulphur is injected through dried air in a burner operating at 1000 °C to form sulphur dioxide (10.5% SO2). The SO2 gas is then cooled in waste heat boiler no.1 before being fed to a four pass converter which provides 99.5% SO2 conversion to sulphur trioxide (SO3). The SO3 gas is the absorbed by 98.5% H2SO4 through the inter-pass & final tower to make more concentrated acid and dilute it with water back to 98.5% H2SO4 in acid pump tanks and dispatched to storage tanks. The manufactured Sulphuric acid is supplied to a variety of industrial manufacturing customers includes Pulp & Paper industry, Mining industry, Chemical manufacturing industry etc. During the 1st quarter of the year 2007, Chemical Initiatives undertook a study to up rate the sulphuric acid plant output by 10% (i.e. from 500 tpd to 550 tpd).

Jan 1, 2009

By Siyabonga Malevu

Chemical Initiatives? Umbogintwini plant is the production facility of Chemical Initiatives? business. Umbogintwini?s J Plant manufactures sulphuric acid. The plant was designed and built by Simon Carves, and was commissioned in 1974. The plant was designed to produce 500 tons/day of Sulphuric acid (H2SO4) at maximum rates. The Sulphuric acid manufacturing is through the famous contact process whereby liquid Sulphur is injected through dried air in a burner operating at 1000 °C to form sulphur dioxide (10.5% SO2). The SO2 gas is then cooled in waste heat boiler no. 1 before being fed to a four pass converter which provides 99.5% SO2 conversion to sulphur trioxide (SO3). The SO3 gas is the absorbed by 98.5% H2SO4 through the inter-pass & final tower to make more concentrated acid and dilute it with water back to 98.5% H2SO4 in acid pump tanks and dispatched to storage tanks. The manufactured Sulphuric acid is supplied to a variety of industrial manufacturing customers includes Pulp & Paper industry, Mining industry, Chemical manufacturing industry etc.

Jan 1, 2009

"What is your assessment of the minerals business?My experience with mining has been primarily in the coal sector until about 10 years ago, when I also became heavily involved in the aggregates and industrial minerals sectors. I have also had peripheral involvement through family and partners in the gold sector, with just enough exposure to gold to become fascinated. In 1994, I visited Ghana and considered the possibility of taking an expat assignment at a surface gold mine that had just been started.It is not news that the coal sector in this country has suffered tremendously in recent years. Especially hard hit is the central Appalachian region, where a number of factors combined have had a devastating effect on production, jobs and the economy. These factors include federal regulations affecting coal production and use, higher production costs and decreasing market share of Appalachian coal by the switch from lower sulfur coal in favor of lowercost, higher sulfur coal from the Illinois Basin, as utilities have installed scrubbers to comply with Phase II of the 1990 Clean Air Act Amendments. Nationally, the lower cost of natural gas has been a huge factor affecting coal use. In Kentucky, for example, which exports to other states around 70 percent of its coal, those markets are disappearing, as utilities close coal units in favor of natural gas. This is a structural change in the electricity market, and one that will become more pronounced as federal greenhouse gas regulations are implemented.We often hear the phrase, "the war on coal." While there are certainly a number of market factors affecting coal production and use, this phrase captures a different element that is all too real. The attacks have come from environmental activist groups for many years; from some in the media and, in the last few years, from a White House administration that believes strongly in alternatives to coal. Then, there really is an alternative to coal in the form of the previously untapped unconventional gas reserves that allowed utilities to move away from coal.Coal mining will continue in this country. In fact, it appears that our production is holding fairly steady at about a billion tons a year. And predictions that I have seen indicate this will continue for the next few years. What impact the Environmental Protection Agency’s Clean Power Plan will have beyond 2020 is another question.What do you feel is the future of the minerals industry - near term and longer term?Our society depends on the future of minerals in this country being strong. Near term, we are going through some of the typical cycles. Having also been involved in aggregates during the last few years, the business follows government infrastructure projects, such as highway construction and public and private sector development. Those sectors are heavily dependent upon government spending and a strong economy. Increased spending in those sectors, which appears to be on the horizon, should provide additional market shares for aggregates."

Jan 1, 2014

By Alan A. Campoli

The mining industry has long been searching for an effective structural application that prevents weathering and falls of loose rock, debris, and sediment. J-Crete is a fiber-reinforced, engineered, cementitious composite rock application that is designed, tested, and successfully utilized as such a material. Laboratory evaluation of J-Crete material properties has shown the final compressive strength to be in excess of 7,300 psi (50.34 MPa), with 24 hour strength in excess of 1,500 psi (10.34 MPa). The flexural tensile strength is in excess of 600 psi (4.1 MPa) and is provided through a unique combination of polyvinyl alcohol (PVA) fibers activated by a proprietary liquid additive that prevents them from clumping and enables even distribution throughout the grout. Tensile bond strength in excess of 350 psi (2.4 MPa) at 28 day cure tightens the strata and holds loose material in place. Practically impervious to gas and liquids, J-Crete protects strata against long-term weathering, does not require screening to be effective, and has proven to be a successful waterproofing material. J-Crete has demonstrated the potential to alleviate coal mine roof cutters in soft, wet clay formations. J-Crete reinforces coal mine ribs by bonding directly to the rib, conforms to the strata, strengthens the rib, and eliminates sloughing due to long-term weathering; stabilizes coal mine entries by bonding directly to the brow and roof, and creates a monolithic shell with double reinforced corners.

Jan 1, 2012

By K. M. Stone, N. J. G. Masson, A. C. Woollett

The Jabali zinc deposit, in Yemen, contains at least 9.4 Mt at a grade of 10.7% zinc, 2.2% lead and 77g/t silver. The zinc occurs as smithsonite with minor hydrozincite. The Jabali ore does not produce a zinc concentrate of sufficient grade to be acceptable to conventional smelter/refineries, and it has been necessary to formulate a less conventional development plan. This involves the construction of a mine and concentrator at Jabali and a metal production facility using a new flowsheet designed specifically for the treatment of oxide material, at Yanbu, in Saudi Arabia. In order to give the facility the necessary economies of scale, the Jabali concentrate will be supplemented by feed from other deposits, this may be either oxide or sulphide material. The paper outlines the geology and proposed mining and treatment operations at Jabali, the flowsheet for Yanbu and presents preliminary costs for both operations

Jan 1, 2002

By K. M. Stone, N. J. G. Masson, A. C. Woollett

The Jabali zinc deposit in Yemen contains at least 9.4 Mt (10.4 million st) of ore at a grade of 10.7% zinc, 2.2% lead and 77 g/t (2.2 opst) silver. The zinc occurs as smithsonite with minor hydrozincite. The Jabali ore does not produce a zinc concentrate of sufficient grade to be acceptable to a conventional zinc smelter, and it has been necessary to formulate a less-conventional development plan. This involves the construction of a mine and concentrator at Jabali and a metal production facility using a new flowsheet designed specifically for the treatment of oxide material at Yanbu, Saudi Arabia. To give the facility the necessary economies of scale, the Jabali concentrate will be supplemented by feed from other deposits, this may be either oxide or sulfide material. The paper outlines the geology and proposed mining and treatment operations at Jabali, presents the flowsheet for Yanbu and estimates preliminary costs for both operations.

Jan 1, 2003

By A Purwodihardjo

Evaluation of the construction method used for the pedestrian underpass construction at Ipswich Road, Brisbane, Australia is presented in this paper. The pedestrian underpass was constructed through the existing railway embankment between Harrogate and O’Keefe Streets on the eastern side of Ipswich Road. This underpass construction is part of the CLEM7 tunnel project (formerly known as the North-South Bypass Tunnel) which is the longest toll road in Australia at a total length of 6.8 km. The jacked box construction technique was initially identified as a preferred option during the tender and concept design phases. However at the final design stage, the cut and cover technique was selected as this method can reduce the construction time and cost significantly. The design and construction teams effectively managed the challenges, complexities and risks associated with undertaking cut and cover tunnel through the existing heavily utilised rail embankment. The on-site construction time for the underpass using the cut and cover technique was reduced to less than 42 hours.

Mar 8, 2011

By Jesus M. Rohena

Concrete pipes and small boxes have been installed by the jacking method. This paper will describe a recent project were large concrete boxes were installed by the jacking method. This project is in the city of Boston, MA. By now everyone in the USA knows something about this project. The project official name is The Central Artery/Tunnel Project (CA/T). This is the biggest public work project in the USA right now, with an estimated construction cost of 14 billions. The main objective of the CA/T project is to replace an existing artery built in the 1950s to increase capacity and safety. One section of the new artery will cross under several railroad tracks near the South Station. To construct the section of the new artery under these tracks, big concrete boxes were installed by the jacking method. The jacking method can be used to install pipes, small concrete boxes, and the CA/T project has demonstrated that big concrete road tunnel boxes can be installed by jacking.

Jan 1, 2003

By C. C. Clark, D. J. Benton, J. B. Seymour, L. A. Martin

"The U.S. National Institute for Occupational Safety and Health (NIOSH) is conducting research on jackleg use and related accidents in underground metal mines. This paper provides an analysis and overview of jackleg drill usage, accidents, operational characteristics and alternatives, based on information from injury reports, legacy research, stakeholder input and published literature. The results indicate that jackleg drills are involved in more groundfall accidents in underground metal mines than any other drill, and jackleg-drill-related injuries are most prevalent at the face in the course of installing initial ground support. Practical mechanized alternatives to jackleg drills for drilling and bolting under incomplete support in narrow underground openings have not yet been realized. Small, versatile mechanized bolting equipment needs to be developed to address jackleg-drill-related accidents and improve safety at mines where jackleg drills are being used. IntroductionJackleg drill is a generic name for a handheld, rotary, percussion rock drill equipped with an attached reaction leg to provide stability and thrust (Fig. 1). All of the drill and leg controls are located near the operator’s handle at the rear of the head portion of the drill. Jackleg drills are classified according to the bore size of their pneumatic pistons, which normally range from 6.03 to 8.26 cm (2.375 to 3.25 in.) (Kurt, 1982; Clark, 2012). Jackleg drills typically weigh 46.7 kg (103 lb), but the weight can approach 54.4 kg (120 lb) after being fitted for operation with drill steel and air and water hoses (McKibbin and Clark, 2001). In underground mines, jackleg drills are commonly used to drill 3.8-cm (1.5-in.) diameter holes up to 1.83 m (6 ft) deep in rock."

Aug 1, 2016

By C. Clark, J. Seymour, D. Benton

"National Institute for Occupational Safety and Health NIOSH is conducting research on jackleg use and related accidents in underground metal mines. This paper provides an analysis and overview of jackleg drill usage, accidents, operational characteristics, and alternatives, based on information from injury reports, legacy research, stakeholder input, and published literature. Jackleg drills are involved in more ground fall accidents in underground metal mines than any other drill. Jackleg-related injuries are most prevalent at the face in the course of installing initial ground support. Alternatives to jacklegs for drilling and bolting under incomplete support in narrow underground openings are not yet available. Small mechanized bolting equipment needs to be developed to address jackleg-related accidents and improve safety at mines where jacklegs are being used. JACKLEG DRILL Description The term “jackleg drill” is a generic name for a class of handheld, rotary, percussion rock drills that are equipped with an attached reaction leg to provide stability and thrust for the drill (Figure 1). All of the drill and leg controls are located near the operator’s handle at the rear of the head portion of the drill. Jacklegs are classified according to the bore size of their pneumatic pistons which normally range from 6.03 to 8.26 cm (2.375 to 3.25 in) [Kurt, 1982; Clark, 2012]. Jacklegs typically weigh 460 N (103 lbs), but their weight can approach 535 N (120 lbs) after they are fitted for operation with drill steel and air and water hoses [McKibbin and Clark, 2001]. In underground mines, jackleg drills are commonly used to drill 3.8-cm (1.5-in) diameter holes 1.83 m (6 ft) deep in rock. Application The jackleg drill is primarily used in underground mines when the size of the ore body, the ground conditions, or the mining method do not permit large openings to be mined using mechanized equipment (e.g., narrow vein mining). Jacklegs are used to drill blast-holes for explosives and also holes for installing ground support. These versatile drills are used in nearly all phases of mining including exploration, development, production, and maintenance [Kurt, 1982; Williams et al., 2007; Chen and McKinnon, 2012]. The jackleg is used to drill holes in rock using drill bits attached to hollow steel bars called drill steels (rotary percussion drilling). After the hole is drilled, the jackleg can be used to install different types of ground support components, depending on the ground conditions and the specific ground support measures that are needed. For example, the jackleg can be used to install expansion-anchor rockbolts or resin-grouted rockbolts using the drill’s rotary-motion feature. On the other hand, the jackleg can also be used to install friction-type Split-Set™ rockbolts using the drill’s percussion (hammer-motion) feature. As shown in Figure 1, various washer-like bearing plates can be installed along with these bolts to provide additional ground support and to help secure surface control products, such as wire mesh and shotcrete that are in turn used to retain small, loose material between the bolts [Clark, 2012]."

Jan 1, 2016

By AIME AIME

SCRIPTURE, statistics and imagination all were drawn upon by the speakers who acclaimed Daniel C. Jackling as recipient of the William Lawrence Saunders Gold Medal for 1930. The award was made at a special dinner at the Ritz-Carlton, in New York, on Oct. 31. Lafayette Hanchett, old friend and associate, said that if it were his task to compress the life story of Daniel Jackling into a single sentence, he could find noth¬ing so appropriate as these words from the 22nd Chapter of Proverbs, "See'st thou a man diligent in his business, he shall stand before Kings." Mr. Jackling's diligence, according to the speaker, his love for his task, have been outstanding in his career. W. S. Boyd, now ranking official in the Jackling organization, cited amazing statistics as to the quantity of copper supplied to industry by the four "porphyry". coppers that are under Mr. Jackling's immediate direc¬tion, as well as by those that, in a sense, owe their existence to the pioneer work at Utah Copper. In the aggregate- 16,000,000,000 lb. of copper having an approximate value of $2,700,000,000 have been produced from disseminated ores since 1905; and of this total 42 per cent came from Utah and the Nevada group. Newcomb Carlton, president of the Western Union Telegraph Co., long an admirer of Mr. Jackling, adroitly drew a picture of a similar occasion in some 'foreign country. He imagined Mr. Jackling being raised to the peerage and whimsically addressed him as Sir Daniel, the Right Honorable Earl of Bingham!

Jan 1, 1930

By J. C. Detweiler

THE Jacksonville plant of Humphreys Gold Corp., operating under leases from National Lead Co. and Rutile Mining Co. of Florida, recovers rutile, ilmenite, zircon, and monazite from an ancient beach deposit containing about 2.5 pct of these minerals in combination. The location of the plant is unique, being situated about ten miles from the center of Jacksonville, Fla., surrounded by a thriving suburb. Two four-lane highways pass within 1 ½ miles of the plant. An expressway now under construction will pass over the tailing pile, within 500 ft of the mine office. The elevation at the plant site is approximately 50 ft above sea level. This is one of two mines producing titanium minerals and zircon in Florida. Another mine is also operated by Humphreys at Starke, about 50 miles southeast of Jacksonville. The Jacksonville deposit extends about six miles in a north-south direction, averaging approximately one half mile wide and twenty ft thick. Values begin at the surface over most of its length and ter-

Jan 1, 1952

By G. J. Simandl

Jade is a commercial term encompassing green, white, black or yellow-brown jadeitite and nephrite. Jadeitite consists of Na-rich pyroxene, whereas nephrite consists of prismatic to acicular amphiboles of the tremolite-actinolite series forming bundles that are randomly oriented and interlocked. Nephrite is tougher (harder to break) than jadeitite. Its fracture strength is about 200 MN/m2 whereas that of jadeitite is about 100 MN/m2. On the other hand, jadeitite has a higher hardness (7 compared to 6.5 on the Mohs scale). There are over fifty known nephrite occurrences in British Columbia (B.C.). These occurrences consist of individual blocks, boulder fields, talus blocks and in situ occurrences. Most of the in situ occurrences are lens or cigar shaped. They occur at, or near the contact of ultramafic/mafic rocks (mainly serpentinites) with cherts, and other metasedimentary or igneous felsic rocks of Mississippian to Jurassic oceanic terranes such as Cache Creek and Slide Mountain. These contacts are commonly interpreted as shear/fault related. In general, it is believed that the B.C. nephrite formed by metasomatic exchange between ultramafic and silica-bearing rocks. Impurities in B.C. nephrite are spinel group minerals (chromite, magnetite, picolite), diopside, uvarovite, titanite, chlorite, and talc. Jadeitite is slightly denser than nephrite and good quality material sinks in methyl iodine. There are no known jadeitite occurrences of economic interest in B.C., but there are at least four geographic areas where favorable lithologies, and metamorphic conditions (Pn) required for the formation of jadeitite coincide. These are Bridge River, Pinchi Lake, Dease Lake, and Jennings River. These areas are known to contain small concentrations of jadeite, or are characterized by blueschist or eclogite-grade metamorphic conditions. Rhodonite and pyroxmangite are MnSi03 polymorphs. These minerals are pyroxenoids and are macroscopically and microscopically very similar. For brevity, both are grouped together under the term "rhodonite". Most of the B.C. occurrences are hosted by late Paleozoic chert sequences and are lens shaped and concordant. The common association of rhodonite with iron formations, jasperoids, and/or volcanogenic sulphide deposits in southwestern B.C. permits the delineation of favorable horizons using magnetic or electro-magnetic geophysical methods. Geographic associations between manganese showings and sulphide deposits, and the hydrothermal chemical signature of the rhodonite occurrences from this area, suggest a genetic link between rhodonite and volcanogenic sulphide deposits. The typical rhodonite rocks consist of rhodonite, pyroxmangite, neotocite, black amorphous Mn-oxides, Mn-bearing garnet, ± epidote, ±chlorite, ±rhodochrosite, ± parakutnah-orite, ± Mn-bearing calcite, ± iron oxides and hydroxides. Garnet ± epidote forms yellow patches and layers within the rhodonite. Within some of the rhodonite occurrences, the garnet is altered to chlorite. Rhodonite-bearing rock is commonly cross cut by secondary manganese oxide veins, creating a characteristic web-like texture. In several localities, the contorted bedding planes are readily recognized. Mn-calcite and quartz also crosscut rhodonite. Rhodonite deposits hosted by high grade metamorphic rocks may contain pyroxmangite. Rhodonite is an important gemstone and ornamental stone in B.C., second only to nephrite in dollar value. B.C. nephrite and rhodonite have been used for the past 100 years in local jewelry and ornamental applications. More recently they have been used in table tops, and they have potential as upscale materials in tile-making. There may be a market for tiles made from lower grade materials that were previously extracted and stockpiled. The prices of nephrite, jadeitite, and rhodonite vary widely with quality, but gem and ornamental grade stones are relatively highly priced materials and they trade world-wide.

Jan 1, 2001