Different types of stones look different because they are different in composition and in how they were formed deep in the earth. Therefore the surface finish and properties of each type of natural stone will differ. It is normal for most natural stones to have minor “flaws” such as small fissures, color variation, light surface pitting, resin filled occlusions and fissures, and small variances on the lustre of the finish.
A stone countertop surface will not be flawless. Some natural stones are near perfect – Such as the hard quartzites. Some granite and marble species have less “flaws” than others. However, most natural stones form a hard and beautiful surface that is inert (will not self-change).
An idiomatic phrase that can be helpful in making decisions about natural stone is the following:
“ not seeing the forest for the trees”
If you are a person that will look at the “forest” and not focus on the “trees” then natural stone is a good choice for you. Conversely, if you are a person that will focus only on the “trees”, then choose your material carefully to avoid disappointment because somewhere there will be minor flaws.
Granite quartzite and marble can come fissured from the earth and cannot be “unfissured”. Fissures are natural cracks and many beautiful stones (most marbles and granites like bianco antico, antique brown, delicatus and some quartzites) are naturally fissured. When the stone slabs/sheets are cut from the large blocks, most surface flaws are repaired by the slab manufacturer with resins to repair and improve the surface finish. But inside the material it stays natural and fissured. Some of the interesting surface features of stone are a result of the underlining fissures.
Running your fingernail along the surface of the material to feel “cracks” only confirms the natural properties of the material.
It is possible for a fissure to open up. If so, a resin is applied to seal the open fissure. The resin forms a strong bond. During fabrication steel or fiberglass bars are often inserted inside the stone along the edge to provide extra strength. There is no need to worry that fissures will cause the stone to fall apart at the sink or anywhere else—it will not.
Can be caused by natural occlusions (empty pockets as could be created by trapped gas), metallic minerals, crystal grain boundaries, etc. The depth of the pitting is minimal – just below the surface and is visible on reflected light. From a stone point of view this type of surface texture is normal and to be expected for nearly all granites and marbles.