Ceramics of indigenous peoples of the Americas
The clay body is a necessary component of pottery. Clay must be mined and purified in an often laborious process, and certain tribes have ceremonial protocols to gathering clay. Different tribes have different processes for processing clay, which can include drying in the sun, soaking in water for days, and repeatedly running through a screen or sieve. Acoma and other Pueblo pottery traditionally pound dry clay into a powder and then remove impurities by hand, then running the dry powder through a screen, mixing it with a dry temper, and then mixing water to create a plastic paste. In preparing the clay, potters spend hours wedging it to remove air pockets and humidity that could easily cause it to explode during firing. The clay then needs to "cure" over time.
Parc Slate Quarry
Moses Kellow, who was born on 5 June 1862 at Delabole, Cornwall, close to one of the largest slate quarries in Britain. His parents moved to Caernarfon some three years later, and besides his school education, his father trained him in engineering and geology. By the age of 20, around 1882, he was managing Parc Quarry. Slate in the Blaenau Ffestiniog region is generally found in veins which slope downwards at an acute angle from the horizontal, resulting in the quarries being underground once the initial surface rock has been removed. The veins are separated by layers of harder rock, often granite or chert, which are called "hards". The slate vein worked at Parc Quarry was about thick, and sloped downwards at about 42 degrees. Unusually, the pillaring line, one of the planes in which rock can be split, was almost horizontal rather than vertical, and the foot joints did not run in a suitable direction to detach slate blocks from the floor of a chamber. Additionally, the rock above the vein was not hard enough to support the roof of large chambers. Because of this, Kellow's father, William, decided in 1880 to work the quarry from the bottom upwards, rather than adopting the more normal practice of working from the top downwards.