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WORLDS MOST POPULAR MARbLES
Explanation, Table A - C, Table D - L, Table M - R, Table S - Z
This article presents the hundred most-offered marbles (in the widest commercial sense). The marbles are described from a different point of view than usual viz. commercial name and type, country, petrographic type, geological age, water absorption, other commercial names, similar stones, and basis of name. Terms are defined first followed by tables of about 100 marbles in alphabetical order which is the main part. The idea for this article was from my experience and observation of the frustration of consumers and the trade in the process of selection, use, care and maintenance of marble as evident from the popular Expert Advice section of www.findstone.com . The data is based on my own research and revaluation of hundreds of web pages and some catalogues. Your questions, comments, corrections and additions are welcomed at email@example.com
Commercial Marbles vs. True Marbles
Marbles in the widest commercial sense are softer natural stones than granites. Marbles are mostly polishable and they can be worked on by softer tools than for granites for cutting, shaping and polishing. The most important mineral is calcite. They are usually suitable for interior applications.
Many stone experts separate limestones, travertines and onyx marbles as individual groups from marbles.
in a narrower commercial sense
are softer natural stones
than granites, while being more dense than limestones and travertines.
Marbles take good polish and are used for more graded purposes (mainly
polished facing and flooring).
in commercial sense are
less dense, with higher water absorption, than marbles. They are not generally
well polishable and are usually used for less graded purposes, as building
stones, honed flooring.
in commercial sense are
softer natural stones than granites, with large pores. They can take good
polish and are used as building stones, flooring and facing.
in commercial sense are softer
natural stones than granites, typically with distinct colour bands. They
can be translucent in thin slabs. Onyxes are well polishable
and used for high graded purposes like marbles.
boundary between marbles and limestones in a commercial meaning is different
than the boundary between marbles and limestones in scientific meaning.
Serpentine marbles are
metamorphosed rocks created from special type of igneous
(in the widest sense) are medium hard and scratchable by a nail,
knife or glass piece unlike granites. Depending on the calcite,
dolomite and serpentine portions, the total Mohs Hardness
for this group is from 3 to 4.
commercial marbles, the larger the pore amount the lesser
is the strength. In true marbles or in true limestones, the
larger the grain size, the lower is the strength, and the greater is the
brittleness, because mineral cleavage manifests more in larger
pattern of commercial marbles is very changeable unlike granites. The
basic property of true limestones, onyx marbles and travertines is bedding
parallel arrangement of particles (manifested in grain size, colour
or shape). Especially limestones and some true marbles can be cut by veins
of different directions. Many limestones contain visible fossil
remnants. True marbles and onyx marbles are composed of visible
calcite (aragonite, dolomite) crystals like granulated sugar. On the contrary,
limestones and travertines are without markable calcite crystals or grains.
Only some parts as fossils or veins can be with crystals. True marbles
have grainy, cloudy, streaky, banded, wavy, brecciated (broken pieces)
Commercial marbles (except serpentinites) are affected by common organic acids such as a lemon acid and vinegar, contrary to granites. They react more with salt acid (HCl) and other common acids. Commercial marbles are not suitable for external use because acid rains (and any rain in less portion) contains acids which decay stones. Water absorption of limestones is larger than common granites, therefore they are more easily destroyed by frost.
How to use the table ?
Explanation of every column in the table is given below. Sample images are in the Stone Album of www.findstone.com but other images can be found elsewhere.
COMMERCIAL NAME, COUNTRY, STATE, PROVINCE & COMMERCIAL TYPE
In the first column, the most frequently used or the most suitable names are presented alphabetically, further country and its part, and commercial type as a marble, limestone, travertine or onyx.
In the column typical colours are presented according to their importance. Some variations are possible.
As mentioned, commercial marbles have sedimentary or metamorphic origin.
Rocks on the earth`s surface are exposed to weathering.
They are fragmented and chemically changed. Formed fragments and solutions
are most often transported by rivers to the sea.
A large part of commercial marbles are limestones formed especially from inorganic remnants of organisms. Some of them were created by precipitation from fresh water (travertines, onyxes) or marine water (oolitic limestones) or accumulation of limestone fragments (carbonate breccias). Some limestones were chemically altered to dolomites.
Limestones are mostly of marine origin. They are composed of calcite (calcium carbonate) or less of aragonite (other modification of calcium carbonate).
During lithification, when pressure and temperature got raised under overlying beds, some calcite grains and fossils were dissolved and later joined by calcium carbonate cement. Pore spaces were diminished and strength was increased.
In some limestones, accumulations of siliceous materials chert nodules or layers are created during lithification. During pressure and temperature action, zig-zag lines (stylolites) are formed in some limestones caused by uneven dissolution (e.g. FILETTO ROSSO).
An important factor for compact limestone origin is time and higher temperature and pressure during a mountain formation. Folded and deformed limestones are usually more compacted than undeformed ones. During deformation, many limestones were broken to pieces and then fissures among them were filled by calcite veinlets and veins of different orientation (e.g. ROJO CORALITO).
Limestones which were uplifted close to earth`s surface are affected by water, which dissolves limestone (and also marble) beds and caverns and cavities are formed. Cherts, stylolites and cavities are defects during limestone and marble working.
Limestones are mixture of calcium carbonate crystals of different size:
· microscopic particles of calcite (aragonite) up to some tens of micron
· grains of fossil remnants and their pieces
· grains of ooids (minute round particles formed in dynamic tropical seas)
· grains of pellets (minute particles as product of animal metabolism)
particles are minute pore spaces that can be filled in different portion
· fossiliferous (bioclastic, skeletal, shelly) limestones are composed from fossils or their parts. These limestones contain various shells and skeletons, like shells, clams, mussels (ROJO ALICANTE), special shells rudists (AURISINA), algae (JURA MARMOR), algal oncoids (bOTTICINO), crinoids - sea lilies (CREMA MARFIL), and large single-celled organisms - foraminifers (CHIAMPO with nummulites)
· micritic limestones (microcrystaline limestones) are made of mud size calcite particles of chemogenic or biogenic origin and microscopic skeletons of foraminifers (ROSA PERLINO)
· nodular limestones as a type of micritic limestones are composed of rounded nodules to some cm formed probably during solid rock formation (ROSSO VERONA)
· stromatolitic limestones banded limestones created especially by blue-green algae activity (SERPEGGIANTE)
· oolitic limestones contain ooides (PORTLAND)
· limestone breccias (carbonate breccias) are rocks of cemented angular fragments of older limestones, e.g. destroyed parts of coral reefs (bRECCIA PERNICE).
They are fresh water limestones formed by precipitation of calcium carbonate (calcite, aragonite) from hot of cold mineral springs. Pores come from carbon dioxide escaping or from destroyed algal or plant bodies. Travertines can be partly used like external stones because their large pores are not destroyed by frost. athough large pores are disadvantageous because of its difficults maintenance.
They are created by calcite or aragonite precipitation especially in caves. Onyx marbles are compact-usually banded rocks or sometimes translucent.
METAMORPHIC ROCKS were formed by the recrystalization of sedimentary or magmatic rocks under the earths surface during raised pressure and temperature conditions. Metamorphism follows lithification in higher temperature and pressure. Transition between lithification and metamorphism is in the 100 200 ΊC span. Appearance of new minerals is substantcial feature of metamorphism.
True marbles, serpentine marbles and serpentinites are commercial marbles of the metamorphic origin.
Pattern can be homogenous (THASSOS WHITE), banded (MAKRANA DOONGARI), streaked (VOLAKAS), veined (GRIGIO CARNICO), brecciated (ARAbESCATO), cloudy (NUVOLATO APUANO).
Marbles ( true marbles in petrographic sense )
Marbles are metamorphosed limestones or dolomites. During metamorphism when pressure and temperature are raised, calcite crystals of limestones are further reduced in number and increase in size. Crystals interlock closely to give increased strength and decreased pore spaces. Calcite marbles (or simply marbles) are formed from limestones, while dolomite marbles from dolomites. Some new minerals appeared in marbles created from admixtures in limestones. Marbles have a granular appearance from about 0.1 to some milimeters crystals.
The larger the crystals, the less the strength, & more the brittleness in marbles. Dolomite marbles are usually harder, heavier, more brittle, less polishable and have higher water absorption, than limestone marbles. Dolomite mineral is more resistant against acids than calcite.
They are green metamorphic rocks composed of serpentine (Mg silicate) domination. They are formed by metamorphism of ultrabasic igneous rocks (e.g. peridotites).
Serpentine marbles (ophicalcites)
They are green metamorphic rocks composed of calcite and serpentine (some are reddish with hematite admixture). These mixed rocks were created during mountain building processes like the serpentinites.
of the stone is determined in the table by the geological time unit when
the stone was created by the geological process. In some cases the
older the stone the larger the strength, and the smaller the water absorption
Original rocks for metamorphic rock can be formed much earlier than where
metamorphism changed the rocks. For instance, limestones can be created
in Paleozoic, but they were metamorphosed in Terciery.
The basic geological periods with their ages are:
Quaternary (0 - 2 million years)
Neogene (2 25 million years)
Paleogene (25 65 million years)
Cretaceous (65 135 million years)
Jurassic (135 205 million years)
Triassic (205 250 million years)
Permian (250 295 million years)
Carboniferous (295 355 million years)
Devonian (355 415 million years)
Silurian (415 440 million years)
Ordovician (440 - 495 million years)
Cambrian (495 - 540 million years)
Proterozoic (540 - 2500 million years)
Archean (2500 - 4550 million years)
WATER AbSORPTION bY WEIGHT
The percentage of water absorption into stone by weight is determined by the ratio of absorbed water weight and stone weight. Values have been re-evaluated from many sources and they are rounded off. Values in brackets are less reliable because of small amount of data or estimation according to similar stones. The stage of limestone compactness is presented .
OTHER NAMES AND VARIETIES
Lless used or less suitable names and varieties are presented. Many are not quite correct because the word order is reversed or they are incorrect because of wrong spelling or have been mistaken for another stone.
This column can help stone specialists and customers to find similar stones. A stone is similar to another stone by its appearance: colour(s), grain size and particle pattern (arrangement). A stone is partially similar to another one, when some feature is not such evident. In this column, there are also additional stones not covered in the Commercial Name and Other Names columns. Use "Ctrl+F" or "Find in Page" feature of your computer to find your stone in the Other Names or Similar Stones columns.
bASIS OF NAME
Commercial names have different origins. The majority of names are derived from a geographic area or colour. The geographic site could be the quarry place, nearby town or the state. The colour is described in English, Italian, Spanish or other languages. Some stones have their names according to colours of precious stones, plants or animals.
Explanation of some terms in the text above:
K= Potassium, Mg= Magnesium, Fe= Iron, Al= Aluminium, Na= Sodium, Ca= Calcium
Algae plants: some of them produce calcium carbonate in their tissue
Aragonite mineral: calcium carbonate CaCO3, crystal structure other than calcite
bedding - parallel arrangement of particles manifested in grain size, colour or shape
biogenic - of organism remnants
Calcite mineral: calcium carbonate CaCO3, crystal structure other than aragonite
Calcium carbonate - CaCO3, calcite or aragonite according structure
Cherts siliceous sedimentary rocks: siliceous layers or nodules inside limestones
Chlorites group of minerals: silicate similar to micas with aluminium, magnesium and iron
Conglomerate - solid sedimentary rock composed from rounded particles over 2 milimeters
Dolomite mineral: calcium magnesium carbonate CaMg (CO3)2
Foraminifers - single-celled organisms
Fossils remnants of shells, skeletons or tests of organisms; also impressions of organisms
Graphite mineral: modification of carbon C
Hematite mineral: ferric oxide Fe2O3
Igneous rocks - or magmatic rock are formed by crystalization from magma (melt)
Limonite mineral: ferric hydrate FeO(OH).nH2O
Lithification - process by which unconsolidated rock-forming materials are converted into consolidated or coherent state. Compaction - pressure decreases pore space between particles. Cementation - deposition of minerals in pores.
Metamorphic (metamorphosed) rocks - sedimentary or igneous (magmatic) rocks that were altered by heat and/or pressure
Micron - micrometer, one millionth of a meter
micritic - composed of micrite
Mohs Hardness - determined according to a relative scale which consists of ten minerals arranged in order of their increasing hardness
Nodules oval (up to some cm) particles formed during sedimentation or lithification
Nummulites lens-like or coin-like large single-celled organisms
Oncoids oval coated-grains of calcium carbonate formed by algae of foraminifera
precipitation - chemical or biogenic process where solid material is appeared from solution
Petrography branch of geology concerned with rock description
Pyrite mineral: sulphide FeS2
Rudists special Cretaceous reef-formed shells
Serpentine mineral: hydrated silicate of magnesium and iron
Sedimentary rocks - formed from deposition of rock fragments and fossil remnants, or precipitation from solutions
shale - solid sedimentary rocks composed of microscopic particles of clay
Stylolites zig-zag lines which are remnants after uneven dissolution of limestones; contain clay minerals and ferric oxides and hydrates
Translucent light passes through the mineral but the object viewed is not clearly outlined
Veins, veinlets areas of various directions which cross rock (like lines on stone slabs); fissures formed mainly by rock deformation filled by calcite
Weathering processes of mechanical disintegration and chemical decomposition of surface rocks
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Copyright Dr. Daniel Pivko