What type of joint is a quirk mitre?

A quirk mitre is specifically designed for use at outside corners where two adjoining stone or masonry units meet. This type of joint helps to create a clean, aesthetically pleasing finish at the corner and accommodates the natural expansion and contraction of the materials. The unique design of the quirk mitre allows for the edges of the stones to be cut at an angle, which helps minimize the visibility of the joint and provides additional structural integrity to the corner.

The other options do not accurately define the quirk mitre, which is specifically tailored for external applications rather than internal corners or decoration. While joints for attaching different materials or those intended for internal corners have their functions, they do not pertain to the specific characteristics and application of a quirk mitre. Additionally, while decorative joints exist in masonry, they serve a different purpose than the practical application of the quirk mitre at external corners.