Glossaries › Geology terms glossary
Geology terms glossary page 6
Geology terms explained in plain English. 899 words and meanings, most familiar first.
| Word | Meaning |
|---|---|
| pyrophyllite noun | A soft, pale aluminosilicate mineral, somewhat resembling talc. |
| pyroxene noun | Any of a group of crystalline minerals containing silicates of iron, magnesium and calcium. |
| pyroxenite noun | A heavy, dark igneous rock consisting mostly of pyroxene minerals with smaller amounts of olivine and hornblende. |
| pyroxenoid noun | Any of a large group of minerals physically resembling pyroxene |
| pyrrhotite noun | A weakly magnetic ferrous sulfide mineral, FeS. |
| quartzite noun | A metamorphic rock from sandstone, consisting of interlocking grains of quartz. |
| realgar noun | A mineral, arsenic sulfide (AsS), often associated with orpiment and stibnite in lead, silver and gold ores. |
| recrystallization noun | The process of existing grains in metamorphic rocks changing size. |
| retinite noun | Any of various resins, similar in appearance to amber, associated with brown coal. |
| rhodochrosite noun | A crystalline mineral composed mainly of manganese carbonate MnCO3. |
| rhodonite noun | A manganese inosilicate mineral with some substitution by iron and magnesium, of composition (Mn2+,Fe,Mg,Ca)SiO3. |
| rhyolite noun | An igneous, volcanic (extrusive) rock, of felsic composition, with aphanitic to porphyritic texture. |
| rimrock noun | An outcrop of hard rock, often in the form of a cliff at the edge of a plateau, that forms the margin of a gravel deposit |
| rottenstone noun | A soft, friable limestone, used in polishes. |
| rutile noun | The most frequent of the three polymorphs of titanium dioxide, crystalizing in the tetragonal system, TiO2. |
| saccharoidal adjective | Having a texture like granulated sugar. |
| samarskite noun | A shiny black radioactive mineral that contains a complex mixture of rare earth oxides |
| saponite noun | A trioctahedral smectite mineral. |
| sapphirine noun | A rare silicate of magnesium and aluminium (with iron as a major impurity), named for its sapphirelike colour. |
| sapropel noun | An aquatic sludge-like sediment rich in organic matter formed in oxygen-free areas at the bottom of lakes, seas etc. |
| sard noun | A variety of carnelian, of a rich reddish yellow or brownish red color. |
| sardius noun | Sard |
| scheelite noun | A mineral composed of calcium tungstate, with the chemical formula CaWO4; an important tungsten ore. |
| schistose adjective | Of or relating to schist. |
| schistosity noun | The quality or state of being schistose. |
| schlieren noun | Irregular streaks of different composition in some igneous rocks. |
| schorl noun | The most common variety of tourmaline. |
| scolecite noun | A monoclinic-domatic mineral containing aluminum, calcium, hydrogen, oxygen, and silicon. |
| sectile adjective | Capable of being cut smoothly with a knife. |
| sedimented adjective | Deposited from sediment |
| sedimentology noun | The study of natural sediments and of the processes by which they are formed |
| seismicity noun | A measure or a degree of how seismic a region is or how prone it is to earthquakes. |
| seismogram noun | The graphical output from an accelerograph or seismograph. |
| seismometer noun | A device used by seismologists to detect and measure seismic waves and therefore locate earthquakes etc; a seismograph. |
| selenite noun | A soft, glassy form of gypsum (chemical formula CaSO4·2H2O). |
| sepiolite noun | A hydrated magnesium silicate, clay mineral used for carving into decorative articles and smoking pipes. |
| septarium noun | A flattened concretionary nodule, usually of limestone, intersected within by cracks which are often filled with calcite, barite, or other minerals. |
| sial noun | The rocks rich in silicon and aluminum that form the upper layer of the earth's crust, which lies beneath all continental landmasses. |
| silicification noun | Impregnation with silica; petrification. |
| sillimanite noun | A fibrous neosilicate mineral, polymorphic with andalusite and kyanite, with the chemical formula Al2SiO5. |
| slickenside noun | A smooth, striated rock surface caused by the friction of one mass sliding over another |
| slicking noun | A narrow vein of ore. |
| smaltine noun | Smaltite |
| smaltite noun | A variety of skutterudite with the chemical formula (Co,Fe,Ni)As2, crystallizing in the cubic system. |
| smaragdite noun | A green foliated kind of amphibole, observed in eclogite and some varieties of gabbro. |
| smectite noun | Any of many clay phyllosilicate minerals that have a relatively open structure. |
| smithsonite noun | A mineral form of zinc carbonate, ZnCO3, mined as an ore of zinc or as an ornamental stone. |
| soapstone noun | A soft rock, rich in talc, also containing serpentine and either magnetite, dolomite or calcite. |
| solifluction noun | Soil creep caused by waterlogged soil slowly moving downhill on top of an impermeable layer. |
| spathic adjective | Having good cleavage. |
| sperrylite noun | An isometric-diploidal tin white mineral containing arsenic and platinum. |
| spessartine noun | A type of garnet, a neosilicate of manganese and aluminium with the chemical formula Mn32+Al2(SiO4)3. |
| sphalerite noun | A yellow, brown or black, sometimes red, green white or colorless mineral with cubic crystals, of a chemical formula (Zn,Fe)S, often containing also minor metals, such as cadmium, gallium, germanium and indium. |
| sphene noun | Titanite |
| spodumene noun | The mineral lithium aluminium inosilicate (LiAl(SiO3)2), a pyroxene and ore of lithium, sometimes regarded as a gemstone, which may be greenish, yellowish or pinkish in appearance. |
| stade noun | In glaciation during which a secondary advance of the glaciers occurs. |
| stalactite noun | A secondary mineral deposit of calcium carbonate or another mineral, in shapes similar to icicles, that hangs from the roof of a cave. |
| stalagmite noun | A secondary mineral deposit of calcium carbonate or other mineral, in shapes similar to icicles, that lies on the ground of a cave. |
| staurolite noun | A dark brown nesosilicate mineral that has crystals that cross and intergrow |
| staurolitic adjective | Of or relating to staurolite; resembling or containing staurolite. |
| steatite noun | Soapstone (often synonymous; more information at soapstone § Terminology). |
| steatitic adjective | Containing, resembling, or relating to steatite. |
| stibine noun | Stibnite. |
| stilbite noun | A tectosilicate zeolite mineral consisting of hydrated calcium aluminium silicate, common in volcanic rocks. |
| stoss adjective | Facing towards the flow of a glacier or fluid. |
| stratiform adjective | Descriptive of rocks with extensive horizontal development |
| stratigraphy noun | The study of rock layers and the layering process (stratification). |
| stromatolitic adjective | Of or relating to a stromatolite. |
| strontia noun | A pale earth composed of strontium oxide (SrO) |
| strontianite noun | A grey or yellowish mineral, SrCO3, strontium carbonate, that is an ore of strontium. |
| subaerial adjective | Formed, located or occurring on the Earth's land surface; contrasted with subaqueous |
| subcontinental adjective | Located or occurring beneath continental crust. |
| subcrustal adjective | Underneath the crust (of the Earth) |
| subepoch noun | A geochronologic unit comprising one or more ages, being a period of generally agreed significance within an epoch. |
| sunstone noun | A translucent form of feldspar having flakes of hematite, used as an ornamental stone. |
| Word | Meaning |
|---|---|
| supergene adjective | Leached and then deposited by descending waters |
| syenite noun | An igneous rock composed of feldspar and hornblende. |
| sylvanite noun | Silver gold telluride, a soft metallic mineral ranging in color from steely gray to almost white. |
| sylvite noun | An evaporite, consisting of potassium chloride KCl, also found in fumaroles. |
| syncline noun | A concave-upward fold in rock strata |
| tantalite noun | A dark-brown mineral that is an ore of tantalum and niobium, of the chemical formula (Fe, Mn) Ta2O6. |
| taxite noun | A volcanic rock that contains coloured streaks of different mineral composition |
| taxitic adjective | Relating to, or composed of taxite |
| tectonically adverb | Involving tectonic plates. |
| tenorite noun | A mineral form of cupric oxide |
| tephra noun | The solid material thrown into the air by a volcanic eruption that settles on the surrounding areas. |
| tephrite noun | An igneous rock consisting essentially of plagioclase and either leucite or nephelite, or both. |
| terrane noun | A block of the Earth's crust that differs from the surrounding material, and is separated from it by faults. |
| terrigenous adjective | Derived from the erosion of land-based rocks. |
| tetrahedrite noun | A complex ore of copper, a mixed sulfide of copper, iron, zinc, silver and antimony. |
| tholeiite noun | An igneous basaltic rock, formed from magma rich in magnesium and iron. |
| thoria noun | The rare earth thorium oxide. |
| thorianite noun | A radioactive mineral containing thorium dioxide (ThO2) plus oxides of uranium, lanthanum, cerium neodymium and praseodymium in smaller quantities. |
| thorite noun | A radioactive mineral, composed mostly of thorium silicate (ThSiO4), along with silicates of uranium and the rare earths. |
| tiemannite noun | An isometric-hextetrahedral grayish white mineral containing mercury and selenium; mercury selenide, chemical formula HgSe. |
| tillite noun | Glacial till cemented into a solid rock. |
| titanite noun | A mixed calcium and titanium neosilicate, CaTiSiO5, once known as sphene. |
| toadstone noun | A soft, earthy variety of trap-rock of a brownish-grey colour, looking like an argillaceous deposit. |
| topotype noun | Type locality |
| tornillo noun | A low-frequency seismic event associated with volcanoes |
| tourmaline noun | A complex black or dark-coloured borosilicate mineral, compounded with various chemical elements and considered a semi-precious stone. |
| trachyte noun | A pale igneous rock consisting mostly of potassium feldspar and plagioclase. |
| trachytic adjective | Relating to, or composed of trachyte |
| transmissivity noun | A measure of the capacity of a saturated aquifer to transmit water horizontally. SI units: m²/s. Symbol: T. |
| trappean adjective | Of or pertaining to trap; of the nature of trap. |
| trappose adjective | Of or relating to trap. |
| trappous adjective | Of or relating to trap. |
| trass noun | A white to grey volcanic tufa, formed of decomposed trachytic cinders, sometimes used as a cement. |
| travertine noun | A light, porous form of concretionary limestone (or calcite) deposited from solution, and sometimes quarried for building. |
| tremolite noun | A pale grey/green amphibole mineral, a type of asbestos, that is a mixed calcium and magnesium silicate, with the chemical formula Ca2Mg5Si8O22(OH)2; sometimes used in place of common asbestos. |
| trichite noun | A kind of crystallite resembling a bunch of hairs, common in obsidian. |
| triplite noun | A rare manganese-bearing phosphate mineral. |
| troilite noun | A non-magnetic variety of the ferrous sulfide mineral pyrrhotite that occurs in most meteorites |
| trona noun | An evaporite, consisting of mixture of sodium carbonate and sodium bicarbonate, Na3HCO3CO3·2H2O. |
| turbidite noun | Any sedimentary deposit formed by a turbidity current. |
| turgite noun | A ferric hydrate, 2Fe2O3H2O, closely related to hematite and limonite. |
| ulexite noun | A white mineral with triclinic crystals, NaCaB5O9·8H2O. |
| ultrabasic adjective | Ultramafic |
| unakite noun | An altered granite composed of pink orthoclase feldspar, green epidote, and generally colorless quartz. |
| unconformable adjective | Exhibiting unconformity. |
| unconformity noun | A gap in the stratigraphic record at a site, resulting from erosion having outpaced deposition over the interval in question. |
| undersaturated adjective | (of igneous rock) Having minerals without free silica |
| underthrust verb | To thrust under another |
| unveined adjective | Not having a geological vein. |
| upfold noun | An anticline. |
| upfolding noun | An upfold or anticline. |
| upthrow verb | To throw up (a mass of material) from below, causing a fault. |
| uralite noun | A dark green variety of hornblende or actinolite. |
| urania noun | Any of several impure mixtures of uranium oxides. |
| uraninite noun | Any of several brownish-black forms of uranium dioxide, UO2, (especially pitchblende) that is the chief ore of uranium; it is isomorphous with thorianite. |
| uvarovite noun | A rare chromium-bearing garnet mineral with a vivid emerald-green colour. |
| variole noun | A spherule of a variolite. |
| varve noun | An annual layer of sediment or sedimentary rock. |
| vergence noun | The direction of the overturned component of an asymmetric fold. |
| vermiculite noun | A hydrated silicate mineral which expands on heating; it is used in insulation and as a medium for planting. |
| vesuvianite noun | A yellow, green or brown mineral, a mixed calcium, magnesium and aluminium silicate sometimes used as a gemstone. |
| vuggy adjective | Containing vugs. |
| wacke noun | A soft, earthy, dark-coloured rock or clay derived from the alteration of basalt. |
| whaleback noun | A landform (typically a sand dune) having the form of the back of a whale. |
| willemite noun | A rare mineral, zinc silicate, Zn2SiO4, that is a minor ore of zinc. |
| witherite noun | A yellow-grey mineral form of barium carbonate, BaCO3 |
| wolframite noun | A mineral that consists of a tungstate of iron and manganese; (Fe,Mn)WO4. |
| wollastonite noun | A grey inosilicate mineral, mostly calcium silicate, CaSiO3, found deposited in limestone. |
| wulfenite noun | An orange mineral, lead molybdate, PbMoO4, found in lead veins. |
| xenolith noun | Any piece of rock having a different origin to that of the igneous rock in which it is found |
| zaratite noun | A hydrous basic nickel carbonate occurring in emerald-green incrustations or compact masses |
| zebraic adjective | Having a pattern of broken stripes. |
| zincite noun | A yellow, orange or dark-red mineral form of zinc oxide, often also containing small amounts of manganese, with a chemical formula (Zn,Mn2+)O, an important ore of zinc. |
| zoisite noun | A mineral with orthorhombic crystals, Ca2Al3(SiO4)(Si2O7)O(OH). |
Meanings from Wiktionary (CC BY-SA 4.0). Sources