Reference work entry
When a volcano erupts, the molten magma is thrown into the air at high velocity. The magma rotates due to resistance and tension, and when it lands on the ground, cooled or semi-cooled volcanic bombs are formed. Volcanic bombs have diverse forms and are typically spindle-like, pear-shaped, twist-like, snake-like or clump-shaped. They can be hollow or have a core. For example, some volcanic bombs in Wudalianchi have granitic cores. The key to distinguishing volcanic bombs is the internal colour, pores and the extent of crystallisation with concentric patterns. Volcanic bombs are valuable geological specimens and have high scientific research, ornamental and collection value (Fig. 6).
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