Basic hypabyssal rocks with composition equivalent to gabbro. Crystal, fine-medium particle size, dark gray-gray-black, usually with luminous green structure or secondary luminous green structure. Pyroxene structure means that the average particle size of pyroxene is larger than the average length of plagioclase, which shows the phenomenon that one pyroxene wraps multiple plagioclase; If the average particle size of pyroxene is less than or close to the average length of plagioclase, it indicates that pyroxene is partially wrapped with plagioclase or alternated with plagioclase, which is called hypoglodyte structure. There are different opinions on the genesis of iridescent structure and sub-iridescent structure, which are generally believed to be formed by the early or late crystallization sequence of minerals under low temperature hydrothermal conditions. Diabase with many gaps and synbiotics, or diabase with gap symbiotic structure composed of synbiotics and orthoclase, is called synbiotic diabase or tholeiite. Alkaline diabase contains zeolite, orthoclase, aegirine or aegirine. There are pyroxene and hypersthene in seasonal diabase, and olivine in alkaline diabase.

Diabase is often in the form of bedrock, dike, dike and sheet, and also in the form of neck or strain filled in basalt crater. The above occurrence of diabase is the main sign that distinguishes it from gabbro and basalt. Large-scale diabase intrusions, such as numerous diabase beds or diabase plate geological bodies, are 300 ~ 400 meters thick, which often occur under the condition of medium thickness (about 2000 ~ 3000 meters) in the overlying strata, because magma is easy to penetrate along bedding or fractures. Diabase is a first-class building stone and casting stone raw material.