Mudstone.
Bone tissue is a connective tissue with a stony hard matrix due to the presence of mineral salts, primarily calcium and phosphate, that provide strength and rigidity to the structure. Bones are important for supporting the body, protecting organs, and serving as attachment points for muscles.
The technique that compresses the surface of clay to make it watertight and gives it a sheen is called burnishing. This process involves rubbing the surface of the leather-hard clay with a smooth, hard tool, such as a stone or a metal burnisher, which compacts the clay particles and creates a polished finish. Burnishing not only enhances the aesthetic quality of the pottery but also increases its durability and resistance to moisture.
Limestone would be potentially harder until the clay is fired. The problem we have here is that "clay" is an ambiguous term. There is no homogenous or standard formula for clay. However, clays can generally be formed and baked to become set and hard. This is called firing. Fired clay tends to be quite hard, and depending on the formula, might be harder than limestone.
Stony Plain was named after the stony soil found in the area and the nearby plains landscape. The name reflects the geographical features of the region and its history as a plains region with rocky terrain.
Clay is actually a description of sediment of a specific particle size. As such clay is not necessarily a rock. However when compacted and cemented clay forms claystone which is a sedimentary rock.
A ground up rock and boulders in a hard stony clay is commonly referred to as gravel or rocky clay soil.
Coral reef
That is called "leather hard" clay
Leather Hard
In North Africa, a vast stony desert plain is known as reg.
Semi-hard clay is often referred to as "leather-hard" clay. At this stage, the clay has dried enough to hold its shape but is still pliable and can be easily carved or burnished. It’s an ideal consistency for adding attachments or details to pottery or sculptures before firing.
1)The core of the mango is a part of mango fruit( and not a seed by itself ) and it is called endoscopy in botanical language. 2 ) This endoscopy ( The core ) is hard and stony . It encloses the seed....
Someone that plays much better on clay courts than hard courts. On clay courts, the balls bounce higher, slows down more and spin is exaggerated vs a hard court. Some player's game is more suited for clay courts. Some these players will often do much better on clay courts than hard courts (and visa versa). These are called clay court specialists.
Chara are called "stoneworts" because they have a hard, calcified structure that gives them a stony appearance. This calcified structure helps chara to anchor themselves in aquatic environments and provides support for their growth.
This seems to refer to meteoroids. If they land on Earth they're called meteorites. They are usually stony, but some are metallic.
Hard and dry clay dose not
Terracotta is not a stone, it is clay. It is not hard until it has been fired in a kiln or oven. Also, although the clay is found in nature, the finished product called terracotta is not.