At present,with the continuous construction of railways and highways in China,basalt stones have become a common stone material in construction due to their strong compressive strength,low crushing value,strong corrosion resistance,and strong wear resistance.The formation of their characteristics is closely related to the formation structure of basalt stones.Therefore,the following analysis will focus on the formation structure of basalt stones.
The degree of crystallization and grain size of basalt stones mainly depend on the cooling rate of magma.Slow cooling(such as cooling down a few degrees per day)can generate crystals several millimeters in size or the same size;Rapid cooling(such as cooling by 100℃per minute)can generate small needle shaped,plate-like crystals or amorphous glass.Therefore,under surface conditions,basalt stones usually have a fine-grained to cryptocrystalline or glassy structure,with a few having a medium grained structure.Often containing olivine,pyroxene,and plagioclase crystals,forming a spotted structure.Spot crystals can aggregate in flowing magma,known as clustered structures.These phenocrysts are formed during the process of basaltic magma rising through the crust(lasting from several months to several hours),and can also be formed in large magma reservoirs before eruption.The matrix structure undergoes significant changes,with various transition types between fully crystalline and glassy depending on the thickness of the rock flow,the speed of cooling,and the amount of volatile components.However,the main types are intergranular structure,interstitial structure,and hidden structure,with less secondary bright green structure and bright green structure.
The structure of basalt stones is related to their solidification environment.Basalt stones formed on land often exhibit rope like structures,block like structures,and columnar joints;Basalt stones formed underwater often have pillow like structures.And pore structures and almond structures may appear in various basalt stones.
In explosive volcanic activity,hot basaltic lava erupted from the crater,and with the difference of its consolidation degree before landing,different shapes of volcanic bombs were formed:spindle shaped bombs,Fried Dough Twists shaped bombs,irregular volcanic bombs,and cow dung shaped,cake shaped,straw hat shaped or snake shaped and flat splashed lava clusters.
In the above introduction,we learned that the temperature and environment play a crucial role in the formation process of basalt stones.By introducing basalt stones,we can better use them in construction to improve the efficiency of stone utilization.