Home | About Us | Info | Buy | Sell | To Pay | Images | Library | Advice | Search | RSS Feeds | Site Map | Contact Us  

ADVICE WANTED!   July 31, 2002
www.findstone.com info@findstone.com

Ask any question, share your knowledge, or offer your services!

Limestone Characteristics - General

Physical, chemical, technical characteristics of limestone in general

  General, Marble, Granite, Limestone, sandstone, Travertine
  other, bluestone, slate, onyx, engineered stone, manufacture stone, basalt, pebbles, flagstone, lava

Q 2275: I read a response on the FindStone expert forum by Dr. Hans saying that he had researched 60 limestones for an architect for external cladding. I was wondering if you could share which limestones came out on top. I'm considering honed limestone counters for my house and am looking for the densest, best performing ones. I was told French Beauharnais was a good one. Any information would be most appreciated! Thank you, Nancy, July 22.
R3: Dear Nancy, I can confirm Dr.Hans information. Your mentioned BEAUHARNAIS (or CHASSAGNE BEAUHARNAIS) has porosity 3-15%, but absorption about 1.5 - 2.5%. Much more dense with similar color there is CREMA MARFIL from Spain with porosity 0.2 - 1.3 and water absorption 0.1 - 0.5%.  Daniel, Slovakia 
R2: Dear Nancy and other readers: The posting to which you are referring was in one of the other (?trade) sections to do with supply. Many limestones could have been used but there were strict guidelines that I needed to follow for this type of construction (for example, a thickness of 30mm, mechanical fixings, price, reliable availability, and proximity to saltwater). Limestones are calcareous rocks made up of at least 50% of carbonate mostly in the form of calcite, aragonite, and dolomite. There are other carbonate varieties but these are not significant in the context of building stone. As a group, these carbonate rocks represent about one-fifth of all sedimentary rocks, occur on all continents, and span all ages from recent to very old. Limestones are regarded as non-clastic sedimentary rocks that can be formed from many geological processes. They are texturally, structurally and mineralogically extremely diverse - characteristics which reflect their derivation, environment of deposition, and diagenetic history. Although a large proportion of limestones are biogenic (contain fossil material), there are also chemically deposited limestones which are important as building stone, namely travertine.  

The principal factor which unifies these carbonate rocks is their high reactivity to acids. Acids are a fact of life and here to stay. There are many of them in our home and in our environment. Wine, carbonated drinks, fruits and fruit juices, vinegar, and even some natural waters will react with these carbonate rocks. And there is little that we can do about it!! Many a posh resort and nice residences with originally finely polished or honed limestone surfaces on their bartops or kitchen-tops have discovered this.  

Another key characteristic of limestones is their softness relative to other rocks such as granites. The softness is mainly a function of the mineral composition. Calcite typically has a hardness of 3 on the Mohs scale of hardness whereas dolomite and aragonite are a bit harder (3.5 to 4). Because of this softness, it can be easily scratched by most things in the house such as cutlery, coins, tools, keys, toys, etc., so there should never be the expectation that nicely polished or honed limestone surfaces are going to stay that way for ever.  

A physical feature of limestones which is important geotechnically is its intrinsic porosity. Many limestones, particularly the biogenic ones, have a medium to high degree of porosity. Porosities of 10-30% are not unusual in the French limestones and the famous Australian limestone from Mt Gambier has a porosity of 50%.  
But although technically weak and very absorbent, certain construction techniques (both old and modern) allow them to be used successfully and effectively. In cold climates, however, a porous limestone can suffer rapid degradation due to freeze-thaw cycling and some protection might be required.  

One important structural aspect inherent in most limestones is the presence of very fine, squiggly lines which are often brownish. These structures, called stylolites, are pressure-solution features formed during the compaction and lithification of limestones. Mostly, the brownish colour is due to hydrated iron oxide but there can also be concentrations of clays and/or sulphides. Because these stylolites are natural planes of weakness and can often transmit fluids because they are not fully closed, any expanding clays can react to fluids and physically weaken the limestone.  

A final comment is on the observation that over the last few years or so, a number of "marbles" have reverted to "limestones". In the stone trade, it has been long accepted that any limestone that can be polished can also be called a marble. If a limestone has undergone some post-depositional (diagenetic) modifications some recrystallization will have occurred. The crystals might still be quite small but the crystalline minerals of the limestone will accept a polish. Because marbles are "old hat" and limestone has become the buzzword of many architects, there is now a strong trend to market mildly recrystallized limestones that were once called marbles. Indeed, it is this group that appears to be capturing a significant portion of the stone market. Incidentally, some limestones from Oman and Saudi Arabia were seriously considered for the external cladding as was the beige-coloured Jurastone from Germany. (Dr. Hans), Australia
R1: Dear Nancy: I don't remember the posting you're mentioning. But it doesn't matter. I'm 
personally so "lukewarm" about limestone that I never made it my priority to find out much about it. I just so happen to know that the densest of the bunch (at least to the best of my knowledge) is the Solnhofen stone from Germany (I'm not so sure about the spelling). About the French one you indicate, I have not a clue.
Ciao and good luck, Maurizio, USA
Q 2256: We are an architectural firm working on a project where we will be using limestone on interior and exterior floors, and for interior and exterior walls. Also guide me how to describe the different surfaces I want in general terms. July 18, .
R1: For description of surfaces:
a) rough :- as found in blocks from the quarry
b) sawn:- as cut in a circular block saw or in a gangsaw
c) natural cleft :- as you find in natural slatestone and limestone, or any stone which can be split into layers with chisel
d) bush hammered :-with a multi or single-pointed chisel
e) Chiselled :- with a chisel which leaves white line on hitting a stone surface 
f) flamed :-with a flaming oxy-acytelene or oxy-CNG flame
g) sand-blasted :- hitting a stone surface with high-pressure compressed air with fine sand 
h) Polished
i) honed :- semi-polished. The above are few of the stone finishes u can ask for.
j) pitched face :- where the sawed or quarried surface is removed leaving a rough, irregular scalloped appearance. 
k) chopped :- where a Guillotine - type piece of equipment is used to break the stone again leaving a rough rock face exposed. JVC.   
A 2010: The information I read on this web-site explaining the use and the definition of limestone. with. I am not sure where you have gotten your information. I know there is a lot research that has been done. I have a limestone quarry and this stone is not soft and also weathers very well. I personal know of homes and buildings that have this stone on them and it has been there for 100 years. Tom, June 3,
R2: Dear Tom: In a perfect world, I would have to agree with you and the answer given to you by JVC but we don't live in a perfect world, do we! 
Most importantly, we do not operate in an industry with any serious rules and standards. In as much I always recognized that the majority of the limestone on the marketplace will not create any problem, as a professional stone restoration guy I witnessed all too many cases in which certain limestone did represent a problem. What's worse is that, not even in one single occasion, I was able (nor was anybody else for that matter) to find a solution to any of those problems, other than ripping the stone out! Some solution, uh! Not exactly what end users have in mind, I suspect! So, we all agree that we have a few inherently "bad" limestone. If you add to the mix the total ignorance about stone displayed by distributors and installers then, as a professional, I don't feel like advising anybody to go for it. Just too darn risky. Ciao, Maurizio, USA
R1: I'll have to agree with Tom. One cannot generalize about the suitability of any generic stone type for various purposes. Especially with the sedimentary stones that have not under gone metamorphism. I have been working with many limestones, and several sandstones, both as a mason and a carver for over 30 years. In the area where I live, there are 5 or 6 distinct limestones that are quarried for building stone, and at least a dozen others which are not for various reasons. Experience shows that the stones used are well suited to the task expected of them. It is not an accident that limestone has been the builders choice for many centuries in all corners of the world. It is not difficult to quarry unlike granite and some marbles. It is relatively easy to work, and impose a shape to. The dust created is not toxic like the silicates in sandstone and granite. It weathers well, and is not as hard to maintain as some other stones. No this does not describe every limestone, but it does describe those which have been quarried for many years, and used extensively in construction from ancient Egypt through the magnificent cathedrals of Europe to new construction going up throughout the world today. Would I use limestone for my kitchen work surface? Probably not, although I know those who have and like the result. Would I use limestone for my flooring? Probably yes, and I have in many instances for completely happy clients. Would I use limestone to build my house? Most definitely yes! over any other stone available to me. Thanks for letting me vent.. JVC, USA, Expert Panelist
A 1954: I am an Architect in Albany, NY. I am specifying a limestone cap for a chimney. I need information as to the grade, color and finishes of limestone. Also, the average thickness of a limestone chimney cap. Thank you for your assistance. Rick, May 22,  
R1: Hi Rick.. What color are you looking for? Limestone has a broad range of color from gray/buff to cream/tan to bone white. I even have access to a pink limestone. They will all eventually turn gray when exposed to the elements as in this application. Thickness should be a minimum of 4 inches if it is spanning any considerable distance. We have seen specs from 3 inches up to 12 inches for chimney caps, so the criteria for this would be the look you want. Top surface can be flat, or with a 2 or 4 side wash (slope). Edges can be square and smooth, pitched faced, or carved to a profile. Good Luck, JVC, USA
A 1927: Need information on technical quality limestone for outside. Marc, May 19,
R1: Dear Marc: So do I ... So do I!! Ciao and good luck, Maurizio, USA
A 1486: I am a student and I am doing a project on limestone tiles. I need to know what raw materials you need to make limestone tiles & the by-products produced from those limestone tiles Please help if you can. Thank you for your time. Johanne, USA, March 1.
R2: The raw materials you need to make limestone are at the bottom of the sea all the debris shells, fish, sediment, H2O and just a few million years. The by-products would lower the acid in your top soil. John. UK,
R1: Dear Johanne: Thank goodness you're admittedly a student!! Let me tell you, you still have a lot to study about!! 
Limestone tiles are made with ... Ready for this? LIMESTONE!!! 
In other words, limestone is quarried in blocks; the blocks are cut into slices (slabs); the slabs are then cut into strips (12", or 16", or 18"); the strips are then calibrated for thickness (grinding), then honed and finished; Finally the strips are cut across to make tiles out of them. Maurizio,
A 1287: I hear from some people that Texas (cream) limestone won't stand up to freeze / thaw conditions as well as Indiana limestone. Is this true? Also, which ASTM test results do I look at to determine how well a stone will survive in my mountainous Virginia climate. John, USA, Dec 31. Reply
R3: Water absorption is the most basic physical property and also the most useful. It can also be used as a rule of thumb for freeze / thaw resistance - the lower the water absorption, the higher the freeze / thaw resistance. Jim, Australia.
R2: John.. Texas Creme Limestone has been used all over the country, Canada, and over seas for more than 100 years now. It will hold up in your climate about as well as any limestone. The truth of the matter is that no porous stone will pass ASTM freeze-thaw test as the testing is done on stone that is saturated with water, which should never be the case with stone installed in a vertical situation on a wall. If you are considering the stone for architectural elements in a building, Texas stone will work just as well as any other. If you are considering using the stone for flat work, ie patio or staircase than you might run into a problem. Finally, whatever stone you choose, please consider sealing with a good, breathable sealer to limit the amount of moisture entering the stone. Texas cream is softer than the Indiana stone, but it also has a warmer, distinctive look to it that the Indiana stone does not have. JVC, USA.
R1: John, while it is true that Texas Creme limestone is not as stiff and dense as the Indiana limestone, it has been used successively for exterior applications in many cold climate areas. What is the application you are considering? Are you going to use the material for flat work (Patio or stairs), unprotected wall cap, or for veneer or other architectural features? The application would make a difference, Also, no matter what stone you choose, plan on using a breathable sealer to limit the amount of moisture gaining access to the stone, as all pourous stones are susceptible to freeze thaw damage if water is allowed to saturate the material. JVC, USA.

A 943: Please help me with comparing sandstones and limestones with regards to composition and structure. Craig, March 20, USA,

R1: I will keep it simple for you (if you want it more complicated let me know and I will oblige!). Limestone used to be alive. Sandstone did not. Limestone it's a sedimentary rock that derives from the decomposition of (formerly) living organism and, because of that is mostly made of Calcium Carbonate. That classifies it as a calcite rock Sandstone is still a sedimentary rock that was formed by layers of sand that, somehow, sunk deep into the belly of Mother Earth. Once there, high temperature partially melted the sand, and high pressure bonded the components together. Since it is of an inorganic origination, it's a silicate rock. Is that good enough for you? Ciao, Maurizio, USA,