Original rock materials for waterscape – slate, schist, and shale

In recent years, slate, schist, and shale have been used to make waterscape, and there are more and more cases. The impact obtained from the exquisite surrounding environment coupled with the original and coarse stone texture is impressive. What’s the difference between the three? In this article, let’s talk about the relevant knowledge of these three

01. Differences among slate, schist, and shale

In the process of formation, simply put, under the action of high pressure, the same parent rock will form different metamorphic rocks under different metamorphic degrees, such as the continuous metamorphic process of shale → slate → schist → gneiss. Shale is metamorphosed into slate by temperature rise and pressure; Slate is metamorphosed into schist by temperature rise and pressure; Schist is metamorphosed into gneiss by temperature rise and pressure. Schist is a kind of metamorphic rock with a typical schistose structure, which is the product of regional metamorphism. It is characterized by schistosity structure, which is composed of flake, plate, and fibrous minerals arranged in parallel with each other, with coarse particle size, which can be distinguished by the naked eye. The main minerals are mica, quartz, amphibole, chlorite, etc. The disadvantages are low strength, easy weathering, and poor frost resistance.

Slate is relatively thick, generally more than 1cm, schist is a light metamorphic rock, relatively thin, and the thickness is generally 10 ~ 0.2mm. The thickness of shale is generally less than 0.2mm

Specifically understood as:

1. Definition

A rock formed by dehydration and cementation of clay; Slate is a kind of metamorphic rock with plate structure and basically no recrystallization. The original rock is argillaceous, silty, or neutral tuff, which can be stripped into thin slices along the direction of foliation.

2. Ingredients

The composition of shale is complex. In addition to clay minerals, it also contains many clastic minerals and authigenic minerals.

Slate is formed by slight metamorphism of clayey and silty sedimentary rock or medium acid tuffaceous rock and tuff.

3. Classification

Shale is divided into carbonaceous shale, calcareous shale, sandy shale, and siliceous shale according to its composition. Among them, the strength of siliceous shale is slightly higher, and the rest is relatively weak. The compressive strength of the rock block is 19.61 ~ 68.65 MPa or lower. After immersion in water, it is easy to soften and expand, the deformation modulus is small, and the anti-sliding stability is very poor.

Slate mainly includes argillaceous rock, argillaceous siltstone, and medium acid tuff.

The hardness of shale is generally Proctor hardness coefficient of 1.5 ~ 3, and the Proctor hardness coefficient of dense structure can reach 4 ~ 5, and the hardness of some hard shale is higher. The particle composition of shale is related to its natural particle size and diagenetic reasons. The variation range of particle composition is large, which affects other properties of shale.

Slate is a low-grade product of regional metamorphism, with low temperature and isotropic pressure, which is mainly affected by stress. The metamorphic rock with plate cleavage is mainly composed of argillaceous and silty components and the metamorphic rock with plate cleavage mainly composed of argillaceous and silty components can be used as building stones, steles, inkstones, and other stones.

The original rock of slate is argillaceous, silty, or medium acid tuff. Under the microscope, argillaceous and some sericite, chlorite and siliceous can be seen, and sometimes a small amount of muscovite, biotite, and quartz can be seen; Schist, metamorphic rock, high degree of metamorphism, almost all original rocks have been recrystallized; The grain is coarse, and its grain structure is mainly quartz and feldspar. The content of quartz is generally more than that of feldspar, and the content of feldspar is often less than 25%. It is composed of flake, columnar and granular minerals. Sedimentary rock is formed by the consolidation of argillaceous sediments through diagenesis under sedimentary pressure and temperature; It is mainly clay mixed with quartz, feldspar debris, and other chemicals.

02. Precautions for application of slate, schist, and shale Waterscape

Strictly screen schist and slate; Remove small and broken slate with neat edges; Control the size of a single piece of rock to unify the whole; Before laying slate and schist waterscape, clean the rocks one by one to avoid the problem that it is difficult to clean in the later stage. Dust shall be controlled during construction to ensure cleanliness, so as to achieve a perfect waterscape effect.

Through the above content, I have a certain understanding of the three, and the skilled use of the three in the later stage can also play a certain role. Well, for the time being, I’ll write here first, and then talk later!

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