Granite and marble are natural stones that can be used for surfaces such as floors, walls and kitchen and bathroom counters. Granite is more durable and resistant to etching, staining and scratching compared with marble. So kitchen countertops use granite more often than marble. Marble works great for other areas like bathrooms.
It is usually easy to distinguish marble and granite based on the physical appearance of the rocks. Granite usually consists of many different colors because it is composed of crystals of different colors. Marble, on the other hand, is usually one solid color with some veining patterns. While granite is available in a large variety of colors and patterns, marble offers a smaller variety of light colors. Granite slabs are usually larger in size because granite is a harder, stronger rock compared with marble. The hardness of granite also leads to a shiny, glossy appearance, which marble lacks.
Granite and marble are both porous, which means there are spaces between the crystals that make up these surfaces. When oils, alcohol or other liquids spill on a marble or granite surface and are not cleaned immediately, they tend to percolate into the space between these crystals. This causes staining. Marble is softer, more porous, and stains and scratches more easily compared with granite. Polishing marble increases its resistance to staining, as does using a sealant. While granite is also porous and susceptible to stains (especially compared with quartz), it is less so compared with most marble. Granite is more durable and more resistant to scratching and heat from cookware.
Another disadvantage of marble is dulling and etching. When acidic foods like lime or lemon juice or vinegar is spilled on the surface, it gets etched leaves a dull mark. Over time, marble can become duller. One example is how the Taj Mahal, made of white marble, is being threatened by pollution. Unlike stains, which can be removed to some extent, dulling of marble is an irreversible process.
Because of these properties, granite can be used in kitchen counter tops and on floors, while marble is ideal for less trafficked areas of the home like bathrooms, where it can be used for vanities, tub decks, shower walls and flooring. Marble can create a light and unique look, and can be good for surfaces that will not get much use, or for people who are willing to put in the maintenance work and want their surfaces to have a bit of character.
Since granite and marble are both porous (lighter stones are more porous than darker stones), they absorb liquids from spills. It is recommended to use sealants on both marble and granite to prevent staining. For marble surfaces, resealing is recommended twice a year while for granite resealing is recommended once every two years (the frequency of resealing depends upon how heavily the surface is used).
edit Removing stains
Granite and marble counter tops both typically cost $50 to $100 per square foot, including installation. However, high-end marble tends to be more expensive than equivalent high-end granite.
Granite Countertops are made from granite, a natural stone composed of quartz, feldspar, and mica. Granite is mined in large blocks that are then cut into slabs. Marble rock results from metamorphism of sedimentary carbonate rocks, most commonly limestone or dolomite rock. Marble countertops are hence softer due to the presence of calcium carbonate.The swirls and veins of many colored marbles are due to mineral impurities such as clay, silt, sand, iron oxides, or chert which were originally present as grains/layers in the limestone. The color variation is very little in marble as compared to granite.
Any type of rock could contain naturally occurring radioactive elements like radium, uranium and thorium. Some pieces of granite contain more of these elements than others, depending on the composition of the molten rock from which they formed. If present, these radioactive elements will decay into radon, a colorless, odorless, radioactive gas which may be released from the granite over time.
According to a professor at St. Johns University, approximately 5% of granite seems to be of concern. However another study by National Health and Engineering Inc. found that 39 granite slabs studied had radiation well below European Union Safety Standards.