Meteorites of Martian origin would have to be at or near the top of the list. Very few museums and universities are in possession of them. Burgess shale is also in demand for its evidence of early lifeforms from the Cambrian Period.
EDIT: The title of rarest kind of rock in the world is a close tie between the oldest rock in the world, one piece found in Canada, and one in India, and a "rock" called painite, which there are about 50 pieces of. Though there are more pieces of painite, the mass of all of them combined would be equal to or less than the oldest rock in the world combined.
An Igneous rock
Images made by chipping or rubbing away the surface of a rock are called petroglyphs. These are carvings or engravings created by removing parts of the rock surface to reveal a design or picture. Petroglyphs are a form of rock art found in various cultures around the world.
The heaviest rock in the world is probably the Baobab granite in Australia, which weighs about 1,500 tonnes. This massive rock formation is still attached to the ground and has not been moved from its original location.
Igneous rocks form from magma as it cools and solidifies. Examples include granite, basalt, and obsidian.
The rarest naturally occurring element on Earth is astatine. It is a radioactive element with a very short half-life, making it extremely rare and difficult to study. It is estimated that there is only a few grams of astatine present in the Earth's crust at any given time.
its not a rock but it is the rarest without a mod is emerald ore
The Rarest Kind was created in 2012.
There is a kind of turtle that is very almost extinct. There is only one of their kind remaining in the world.
what is the rare rock ever
The rock.
black
Chinook
it depends where you live but the rarest is a Fennec fox
Back darias
The rarest and most expensive shell in the world is found in the Philippines, the name is Connus Gloriamaris or Glory of the Sea. A few of these were found in Luzon, but mostly found in Lawigan, Bislig City.
There are three kinds of rock in the world: igneous, metamorphic and sedimentary.
The world's rarest dog breed is the New Guinea Singing Dog.