Influence Of Mineral Composition Of Stone On Weathering Resistance Of Stone

Weathering can be divided into three categories according to its nature: physical weathering, chemical weathering and biological weathering. Due to the different temperature, atmosphere, water and biological conditions in each region, the weathering degree of stone is different, and the difference will be very large.
But how can we simply distinguish whether a stone has good weathering resistance, whether it is suitable for outdoor use, and whether it has a long service life? In fact, as long as we know the mineral composition of stone roughly, we can know some of them.
At present, there are more than 100 known rock-forming minerals, and the main rock-forming minerals are only more than 20, among which the eight most common rock-forming minerals are:
Quartz, feldspar, mica, pyroxene, hornblende, olivine, calcite, clay minerals.
Different minerals have different characteristics, which also results in a variety of physical properties of natural stone. The weathering characteristics of different minerals will be analyzed for the main rock-forming minerals.
Quartz, whose mineral stability is extremely high, hardly occurs chemical dissolution, and generally only occurs mechanical fragmentation, has good anti-weathering characteristics.
Feldspar is less stable than quartz, and different feldspars are also different. Generally, the anti-weathering stability of different feldspars is potassium feldspar, sodium-rich acidic plagioclase, neutral plagioclase, and calcium-rich basic plagioclase from high to low.
Mica, the anti-weathering effect of mica is quite different, among which the anti-weathering ability of muscovite is strong, while the anti-weathering ability of biotite is much worse than that of muscovite.
Magnesium silicate minerals (olivine, pyroxene, hornblende, etc.) have weak anti-weathering ability and are rarely retained under weathering, so they rarely appear in sedimentary rocks.
Carbonate minerals (calcite, dolomite, etc.) have very low weathering stability and weak anti-weathering ability, and are easily dissolved in water and transferred along the water.
Sulfate minerals (gypsum, anhydrite), sulfide minerals (pyrite) and halide minerals (halite) have the lowest weathering stability and are most easily dissolved in water and lost along the water.
Clay minerals (kaolin, montmorillonite, hydromica, etc.), these minerals are basically the products of weathering of other minerals, so their weathering stability is quite high and good anti-weathering ability.
The weathering stability of heavy minerals is very different. Some are relatively stable, such as zircon and tourmaline, while others are very easy to weathering.