Certain minerals usually break along flat surfaces while other minerals break unevenly the characteristics is due to the

Cleavage of the mineral causes breakage of minerals unevenly along flat surfaces.

Explanation:

Cleavage refers to breaking of flat surface minerals into many surface. The crystalline structure of mineral determines the cleavage. It is the ability of crystalline materials to divide into “definite crystallographic structural planes”.  

The permanent locations of atoms and ions in crystal are the main reason for the relative weakness, which forms smooth repeating surfaces. They are visible both in the microscope and to naked eye.

a maximum–minimum thermometer. the scales are fahrenheit on the inside of the u and celsius on the outside. the current temperature is 23 degrees celsius, the maximum recorded is 25, and the minimum is 15, both read from the base of the small markers in each arm of the u tube. the bulbs are hidden by a plastic housing.

six's thermometer is a registering thermometer which can record the maximum and minimum temperatures reached over a period of time, for example 24 hours. it is used to record the extremes of temperature at a location, for instance in meteorology and horticulture. it was invented by a british scientist james six, born in canterbury, in 1780; [1] the same basic design remains in use.

it is also commonly known as a maximum–minimum, minimum–maximum, maxima–minima or minima–maxima thermometer, of which it is the earliest practical design.

the thermometer indicates the current temperature, and the highest and lowest temperatures since last reset.