Tuff

Classification：Igneous Rock

Tuff is a pyroclastic rock, a tuff structure and a blocky structure. More than 50% of the debris in the far zone from the crater is less than 2 millimeters in diameter. The composition is mainly volcanic ash. Its appearance is loose, porous, rough, stratified and varied in color, with black, purple, red, white and light green. Tuff is a kind of volcanic clastic rock, which consists of more than 50% of the pyroclastic material with a diameter of less than 2mm. The main component is volcanic ash, its appearance is loose or dense. The layer is called layer Tuff, and the color is varied, with purple red, gray white, gray green and so on. Tuff is a volcano that erupts from the surface of the volcano, with fine particles (which can drift with the wind and can be far away from the crater). It is accumulated and consolidated into the product of rock, mainly in the middle acidity, most of which is revealed in the late Jurassic.

Name: Tuff
Fresh color: gray, light yellow, purple and so on.
The color after surface weathering is black purple, gray green, etc.

Main mineral: volcanic dust
Lump or stratiform is formed by the accumulation of volcanic fines. Sometimes thin layer Tuff is often associated with sediments.
Tuff is a kind of volcanic clastic rock, which consists of more than 50% of the pyroclastic material with a diameter of less than 2mm. The main component is volcanic ash, its appearance is loose or dense. The layer is called layer Tuff, and the color is varied, with purple red, gray white, gray green and so on. According to its pyroclastic elements, it can be divided into: crystalline Tuff, Tuff, and Tuff. Tuff is a commonly used building material. It can also be used as raw material for manufacturing cement and raw materials for extracting potash fertilizer.
The volcano Tuff is short for short. A compacted and consolidated pyroclastic rock is somewhat like concrete in color and morphology. It is mainly composed of crystal chips, cuttings and glassy particles with a particle size less than 2 mm. The detrital material is less than 50%. Soft and porous or dense. According to the composition of volcaniclastic, it can be further subdivided into: Tuff, Tuff, Tuff and Tuff. Generally, the glassy Tuff is easily preserved in the new strata that have not been strongly changed in the times, and its alteration is mostly from dehydration, and the common products are bentonite and bleached soil. Can be used as building material and cement raw material
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Tuff is a volcano that erupts from the surface of the volcano, with fine particles (which can drift with the wind and can be far away from the crater). It is accumulated and consolidated into the product of rock, mainly in the middle acidity, most of which is revealed in the late Jurassic.
The most completely exposed in the China Fujian "South Park" area, so named for the Nanyuan group.
In Jiangxi, Shangrao ehuling near the most completely exposed, so named ehuling group.
It is mainly a set of volcanic rocks of Tuff, tuffaceous sandstone and siltstone interbedded with andesite and trachyte.

Characteristic：
Tuff is a fine grained volcanic detrital deposit, from a volcano
The glassy debris in the rock is transparent and slightly yellow or brown, with tiny lobes or vesicles; in addition, it contains fragmented speckles and solidified lava blocks.

Production:
There is a massive, layered, Pyroclasic Rocks, which is mostly in the vicinity of the volcano, but the thin layer is often associated with the sediments, so it is also found in sandstone, shale, or limestone.

Features：
1. crystal chip, glass dust Tuff: the color is mainly grey and white, and the structure of tuff is massive. The content of crystal chips is less than 10%, and quartz chips are composed of quartz, feldspar and a few dark minerals. The content of glass is 3-10% and glass. Tuffaceous cementation, massive structure, hard rock, thick thick thick layer. It is produced in the far zone from the crater.
2.Tuff: gray and white, and the chip characteristics are the same as above, but only 10-30%. Condensate structure, lump structure. It is produced in the far zone from the crater.
3. melting Tuff: the characteristics of the chip are the same as (1), the gray dark gray, the lava structure, the blocky structure, the cementation material is the lava cementation, and the rock is dense and hard.
4. grain texture Tuff: crystal chip features of the same (1), gray - deep grey, stripe strip (black and white) clear, rhyme structure, lump structure, lava cementation, produced in the nearer zone of the crater, tight and hard rock.
There are also neutral volcanic rocks: andesite and trachyte, which are not quartz. The volcanic rocks of basic and ultrabasic (including pyroxene and hornblende) are relatively rare. These rocks are not consistent with the topics, and they are not described here.

Distinguish：
1, bedding, sandstone is generally clearer or even inclined bedding. Tuff is relatively poor, and there will be no oblique bedding.
2, in terms of color, sandstone is generally homogeneous, while Tuff is relatively heterogeneous.
3, the debris in the sandstone, the sandstone and quartz detrital grinding degree is better, the size is more homogeneous, because of the separation of water through the separation; and Tuff all kinds of geometric forms, crystals have detonation marks, that is, crystal, and the size is more complex;
4, in the upper and lower layers, the sandstone is generally composed of a large sedimentary rhythm with conglomerate, mudstone and limestone, while Tuff is composed of volcanic breccia, volcanic block rocks, sinking Tuff and tuffaceous limestone.