Ore Minerals Under the Microscope (eBook)

An Optical Guide

Bernhard Pracejus (Autor)

eBook Download: PDF | EPUB

2015 | 2. Auflage
1118 Seiten
Elsevier Science (Verlag)
978-0-444-62737-7 (ISBN)

Infos

The Ore Minerals Under the Microscope: An Optical Guide, Second Edition, is a very detailed color atlas for ore/opaque minerals (ore microscopy), with a main emphasis on name and synonyms, short descriptions, mineral groups, chemical compositions, information on major formation environments, optical data, reflection color/shade comparison with four common/standard minerals of a similar color or grey shade, and up to five high-quality photos for each mineral with scale.

In addition, the atlas contains a compilation from some of the prominent publications in the field of ore microscopy presented on a list of 431 minerals.

• Concise, full-color pictorial reference for scientists and geologists
• Explains how to describe and identify microscopic samples of minerals
• Draws material from prominent literature yielding more than 400 different minerals

Dr. Bernhard Pracejus currently works as Associate Professor at the Earth Science Department, Sultan Qaboos University, Sultanate of Oman. He is specialised in Mineralogy, Geochemistry, and Economic Geology and his research concentrates on topics such as the alteration of geologic bodies over time (particularly metal deposits), environmentally friendly remediation of heavy metal polluted effluents and solid wastes from mining activities and other industries, and processes at the Bio-Geo-Interface. He has published various articles in journals such as Ore Geology Reviews, Marine Geology, and Chemical Geology.

Textauszug

Preface to the Second Edition

With respect to genetic interpretations and ore petrography, Ramdohr’s “The Ore Minerals and Their Intergrowths” (Ramdohr, 1969) is probably the most comprehensive study on opaque minerals until now. However, and as stated before in the first edition, it needed to be supplemented by colour photos for as many different ore mineral species as possible; this is done here. All minerals shown in the atlas were only examined in polished sections under reflected light.

Ore minerals generally don’t occur just by themselves and, thus, a number of common gangue minerals as well as supergene alteration phases are part of this book. The latter present valuable clues for the identification of mineral associations, because a number of metals exhibit very typical colours once they occur in their oxidised states: Copper minerals then show green, blue, and sometimes red tinges, cobalt shows pink shades, while iron displays pronounced tones of red, brown, and occasionally green.

The term gangue mineral can be fairly misleading for several reasons: a) it constitutes a more economic term rather than a strict scientific meaning - a particular gangue mineral may be considered as waste in one deposit and as ore mineral in another (e.g., hedenbergite), b) its meaning may shift over time - sphalerite, for instance, was dumped by early miners, while it is being mined nowadays.

A word of caution must also be added, because misinterpretations may stem from the analysis of a genetic environment that has not yet been examined adequately. An example for such a situations can be seen in euhedral quartz crystals embedded in the sulfide matrix of fossil Kuroko-type massive sulfide ores, where fluid inclusions have been used to identify the hydrothermal environment. However, unless a particular sample derives from the stockwork of such a deposit, it will normally contain amorphous silica/opal rather than quartz in its initial stages, as is the case in modern hydrothermal equivalents (e.g., JADE deposit, Okinawa Trough, Japan). Thus, metasomatic/metamorphic overprinting is likely to have caused such a recrystallisation and must be accounted for.

In this second edition, the following changes have been incorporated:

• Microscope pictures now supplement the Explanations to illustrate the respective technical terms.

• Textures are briefly described and exemplified by a typical photo to assist genetic interpretation.

• A tabulated Search Index was added, which is sorted according to reflection colours, minerals are internally ordered with respect to their reflectivity/brightness. Further search characteristics found in the table are pleochroism, bireflectance, anisotropy, internal reflections, and twinning. The last column then presents possible minerals. The intended electronic version of the atlas, in contrast, will contain fully searchable categories linked to successive search parameters and pictures.

• The Mineral Descriptions section has been expanded by some 70 new minerals, now adding up to a total of 502 species together with the species of the first edition. Further optical characteristics incorporated in the mineral info form on the respective left pages of this chapter include the following terms (see also explanations chapter):

- Strunz Group (Strunz (2001; version 9); this provides the mineralogical frame in which the minerals of this book are arranged and presented. The grouping of interrelated compounds also makes sense with respect to optical characteristics because of distinctive similarities within the respective groups. Such semblance also proves to be a valuable tool in the identification of unknown minerals.

- Polymorphism, although not too common, complicates identification (e.g., argentite-acanthite).

- The Compositional Series notes related minerals, such as Au-Ag, which can substitute each other.

- The Crystallographic System may reveal itself through isotropic (cubic) or strongly anisotropic (e.g., hexagonal) optical characteristics or shapes.

- The Point Group illustrates how symmetrical a particular mineral structure is.

- The Type Locality shows the site from which the respective mineral was described first. In addition, further minerals that also have their type locality in the same place from where the described mineral derives are also denoted by in the figure captions of the Mineral Descriptions chapter.

- Optically Similar are those minerals which appear within a particular Strunz sub-group (listed here) or in mineral assemblages of a closely related chemical composition.

- Opacity/Diaphaneity listings are provided, because not all ore minerals are opaque.

- The Common Habit (shape) offers mineralogical and genetic clues for phase identification.

- Average Hardness is difficult to discern directly, but possible when adjacent minerals are sufficiently different in their hardness.

- Twinning is representative for a variety of minerals.

- Cleavage and Fracture, if observed can be typical for many minerals.

• All Mineral Photos (previous and new) were electronically enhanced through an increased resolution (not sharpness) to counter fuzziness introduced by the printing process. The exposure time of all pictures taken under crossed polarisers (XPL) was also incremented to improve the dark images of the first edition, while contrast and saturation were left unchanged.

• Colour-coded Major Mineral Groups, such as elements, sulfides, etc., are printed above the images for a fast overview and reflect the abbreviated Strunz group.

• Where necessary, abbreviations for important minerals are plotted as Labels on the photo to ease the recognition of the most important mineral(s).

• Locality Descriptions for all examined samples are presented in the back of the atlas, sorted according to countries and supplemented by literature references pertaining to the respective localities/countries.

• The large Reference Section now allows for a more comprehensive study of the available literature. Unfortunately, publications for some countries are scarce or completely unavailable.

The most important publications for this atlas were the following ones (excluding those already mentioned above): Barnes and Hay (1983), Blatter (1997), Boström et al. (1979), Cabri and Laflamme (1997), Cairncross (2004), Cook (1979), Dobrovolskaya (1999), Dunn (1995), Dyuzhikov et al. (1999), Excursion-Participants (2002), Favreau and Dietrich (2006), Flach (1984), Garuti et al. (1995), Graeme (1981), Graeme (1993), Graeser (1965), Grokhovskaya (1999), Hammer and Peterson (1968), Hernandez et al. (1999), Holtstam and Langhof (1999), Jahn (1991), Keller (1984), Lahl (2005), Leydet (2006), Lhoest (1995), Lombaard (1986), Martin et al. (1994), Nysten et al. (1999), Ondruš et al. (1997), Parafiniuk and Domanska (2002), Pauliš and Haake (1991), Pawlowski (1991), Ream (2004), Rieck (1993), Sejkora and Tvrdý (2002), Shiga (1987), Sokatsch and Weiss (2001), Stahle et al. (2002), Stekhin (1994), Strunz et al. (1958), Szentpéteri et al. (1999), Torgashin (1994), Torres-Ruiz et al. (1996), Walenta (1992), Watanabe (1959), Watanabe et al. (1960), Watkinson (1999), Weiß (1990), Whitehead (1919), Wilson (1950), Wilson et. al. (1950), Wittern (2001).

Other books on ore microscopy, which were used during the preparation phase for this atlas, are Baumann and Leeder (1991), Craig and Vaughan (1981), Gierth (1989), Mücke (1989), and Oelsner (1960), while Criddle and Stanley (1986) and Rösler (1991) were frequently consulted for optical and mineralogical information, respectively. Further helpful publications on mineralogy and geochemistry were by Harris and Burke (1970), Lawrence (1998), Makeyev et. al. (1999), Mücke et al. (1999), Naldrett (2005), Strunz et al. (1958).

An enormous wealth of data regarding mineral associations from world-wide locations was found at mindat.org - an exquisite source of information, particularly in cases when rare samples were examined for which there was no proper mineral inventory available elsewhere. Further deposit descriptions originated from: binn.strahlen.org, franklin-sterlinghill.com, ge-at.iastate.edu, bergbau-verein-ronneburg.de, geology.neab.net/locality/lainejau.htm,...

Produkt-Details

• Erscheint lt. Verlag: 25.6.2015
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Chemie
• Themenwelt: Naturwissenschaften ► Geowissenschaften ► Geologie
• Themenwelt: Naturwissenschaften ► Geowissenschaften ► Mineralogie / Paläontologie
• Themenwelt: Technik ► Bergbau
• Themenwelt: Wirtschaft
• ISBN-10: 0-444-62737-5 / 0444627375
• ISBN-13: 978-0-444-62737-7 / 9780444627377