INDEX 773 silicon (Si) (continued] general discussion 5:51 geysers 5:59 hot springs 5:59 hydrothermal origins 5:59, 5:60f lakes 5:58 nodular cherts 5:55, 5:57f, 5:58f Precambrian 5:55, 5:56f radiolarian chert 5:54, 5:55f sedimentary environments 5:35-36 silcrete 5:61 siliceous ooze accumulation 5:53, 5:SSf silicified wood 5:61 Tertiary bedded chert 5:54 Rhynie chert arthropods (Arthropoda) 2:274-275, 2:277 fossil mineralisation 3:313 fungi 2:437, 2:438f, 2:439f general description 3:310t hydrothermal activity 5:59-60, S:61f lichens 2:441-442 silica sources biogenic silica 5:52 hydrothermal activity 5:53 lacustrine deposits 5:53 siliceous sediments 5:53 volcanism 5:53, 5:54 terminology 3:570 feldspathoids occurrences 3:541 structure general discussion 3:539 leucite 3:540, 3:540f, 3:541f nepheline 3:539, 3:540f sodalite 3:540, 3:540f, 3:541f geothermal systems 3:113t mineral classification systems 3:501t, 3:502t obsidian 3:269t oceanic manganese nodular deposits 5:114t quartz (SiO ) 3:569-571 amphiboles 3:505 carbonatites 3:223t cementation 5:143, 5:143f, 5:144f chalcedony 3:570, 5:35-36, 5:51, 5:52f chemical composition 3:569-570 chemical diagenesis 1:394 cristobalite 1:368, 3:569-570, 3:570f, 3:571 crustal composition l:406t, 5:174t depth effects 5:63f diagenetic processes 5:145f diaplectic minerals 3:281-282, 3:282f fused minerals 3:28If glauconite 3:542t granites 3:240 hydrothermal fluids 3:629t hydrothermal ore deposits 5:394t industrial uses 3:570 karst landscapes 4:679 kimberlites 3:248t Lagerstatten 3:313 Meteor (Barringer) Crater, Arizona, United States 3:571 mineral analysis l:108t palisade quartz 5:533, 5:534f planar microstructures 3:282, 3:282f sand 5:142 sandstones 5:27, 5:143t, 5:143f shock metamorphic effects 4:221, 5:183t silica 3:570, 3:570f structure 3:570 tridymite 3:540f, 3:569-570, 3:570f, 3:571 types 3:570 ultrahigh-pressure metamorphic rocks 5:533, 5:533f, 5:534f Venus 5:2471 weathering 5:17 siliceous sediments chert 5:53 classification 5:26t occurrence 5:35 silcrete 5:588, 5:61 See also silicate minerals Siljan impact event 4:199 silled basins 4:495, 4:496f sillimanite characteristics 3:562 granites 3:235t, 3:240-241, 3:241 f kimberlites 3:254 metamorphic facies 3:399f, 3:400f, 3:412f94:411f,4:412t phase diagram 3:562f pressure-temperature diagram 3:243f sills l:136f, 3:218t, 3:249 silt 1:561, 3:103t, 5:8, 5:9, 5:11-12, 5:14 siltstone 5:26t, 5:28 Silurian 4:184-193 acritarchs 3:418-428, 4:191 Aeronian Stage 4:185-186, 4:186f, 4:187f,5:511f,5:517f anoxic environments 4:193 Antarctica 1:134 f Appalachians 4:78 apparent polar wander paths 4:153 f Arabia l:142f, l:144f Armorica 2:78 arthropods (Arthropoda) 2:276-277, 3:314f, 4:191 Australia l:226f, 1:229, 3:129, 4:191-192 Avalonia 2:78, 4:191,4:192 background information 4:184 Baltica l:173f, 2:78, 4:191, 4:192 biota 4:191 biozones 4:185, 4:186f, 4:187f, 4:189 Birkhill Shale Formation 4:185 brachiopods South-east Asia l:173f, 1:177f stratigraphic distribution 2:306f trace fossils 4:158, 4:lS8f Brazil 1:317f, l:318f, l:320f Bringewood Formation 4:186f9 4:189 Buildwas Formation 4:186f, 4:188-189 calcareous algae 2:428f Caledonian Orogeny 2:61, 2:62, 2:64 carbon dioxide concentrations 1:206f cephalopods 2.-3S9/", 4:191 Cerig Formation 4:186f, 4:188 China 1:347f, 4:192-193 chitinozoans (Chitinozoa) 3:430, 3:435f, 3:436, 3:436f, 3:438f, 4:191 chronostratigraphy 4:25f climate 4:193 Coalbrookdale Mudstone Formation 4:186f, 4:188-189 conodonts 3:447-448 corals 2:325f crinoids 2:346, 2:347f dating methods 4:190 East European Craton 2:36, 2:38f echinoderms 2:335-337, 2:336f Elton Formation 4:186f, 4:189 fish 2:462, 2:463f fossil fungi 2:437 Fossil Konservat-Lagerstatten 2:274-275 gastropods 2:386f, 2:386-387 glacial/interglacial periods 3:347f glaciation 4:663 Global Standard Stratotype Sections and Points (GSSPs) 5:511 f Gondwana early Silurian 3:129 geological evolution 1:178 palaeogeographic reconstruction 2:78, 3:136f, 4:191f, 4:192, 4:192f tectonic processes 4:191 terranes 1:173f, 3:130f Gorstian Stage 4:186f9 4:187f, 4:189, 5:511 f,5:517f graptolites (Graptoloidea) 2:358f, 2:365f, 2:366, 4:185, 4:186f, 4:187f Gwernfelen Formation 4:186f, 4:188 historical background 4:185 Homerian Stage 4:186f, 4:187f, 4:188-189, 5:511f9 5:517f lapetus Ocean 2:78, 4:193 International Stratigraphic Chart (ICS) 5:517 f jawless fish 2:454, 2:460f Kazakhstan l:173f, 4:191-192 Kopanina Formation 4:189 Lagerstatten 3:310t Laurentia l:173f, 2:78, 4:191, 4:192 Laurussia 4:193 Leintwardine Formation 4:186f, 4:189 Llandovery Series 4:185, 4:186f, 4:187f, 4:188f,5:511f,5:517f Lochkov Formation 4:189 Ludfordian Stage 4:186f, 4:187f, 4:189, 5:511f,5:517f Ludlow Bone Bed 4:185, 4:186f, 4:189 Ludlow Series 4:186f, 4:187f, 4:189, 5:511f,5:517f Ludlow subdivision 4:185 molluscs 2:367