Araal or teppei slates also called “crazy cut” slates. These are slates quarried from the Southern Philippines. These are used as wall cladding for exterior and sometimes interior use. The average size of each piece is from ½ to 1 square meter with thickness up to 3 inches and it is both hard but quite brittle.
Some designers have used this as a substitute for stones to mimic the idea of the traditional bahay na bato which uses Spanish-style solid stone blocks or bricks.
The stone used for the araal slate is called the Philippine Teppei stone. It is classified as andesite, which is a dark, fine-grained, brown, or grayish volcanic rock that is intermediate in composition between rhyolite and basalt.
Reference:
“Araal Slates (Philippine Teppei Stone) from Philippines.” www.stonecontact.com. Accessed September 28, 2020. https://www.stonecontact.com/products-35710/araal-slates-philippine-teppei-stone.