Related by context. Frequent words. (Click for all words.) 55 flints 55 flint 55 chert 53 sedimentary rock 53 calcareous 53 obsidian 52 flint tools 52 microfossils 52 hydroxyapatite 51 calcite 51 zircons 50 carbonized 50 foraminifera 50 soapstone 50 olivine 50 nickel alloy 50 volcanic rock 50 iron oxides 50 Radiocarbon dating 50 spherules 50 lunar soil 50 arrowheads 49 calcium carbonate 49 basalt 49 lavas 49 nacre 49 quartz crystals 49 silicates 49 sintered 48 marine sediments 48 zeolites 48 kerogen 48 silicate 48 salt crystals 47 calcium phosphate 47 quartzite 47 oceanic crust 47 lava tubes 47 graphitic 47 lake sediments 47 graphene sheets 46 aluminum oxide 46 copper oxide 46 stromatolites 46 quicklime 46 nanospheres 46 middens 46 ionic liquid 46 magmatic 46 basaltic 46 clays 46 pumice 46 earthenware 45 feldspar 45 continental crust 45 pottery shards 45 igneous 45 oxidization 45 radioactive decay 45 iron oxide 45 birch bark 45 annealed 45 MgO 45 metal oxides 45 sinter 45 coprolites 45 regolith 45 haematite 45 red ocher 45 siliceous 44 alkali 44 striations 44 mica 44 meteorites 44 Oetzi 44 ceramic 44 fossils 44 lava rocks 44 carbonaceous 44 osmium 44 enamel 44 limestone 44 stalagmite 44 microstructures 44 isotopic 44 agates 44 ejecta 43 musket balls 43 granites 43 petrified wood 43 isotopic composition 43 molten glass 43 solder joints 43 diatoms 43 zirconia 43 magma chamber 43 resistant tiles 43 synthetic polymers 43 apatite 43 sulphide minerals 43 crystals