Large dalmatian stones also widely known as dalmatian jasper. This distinctive material which comes primarily from Mexico is particularly popular with younger rock and mineral collectors.
"Dalmatian" is a trade name which came about because of the stone's spotted appearance which was likened to the breed of dog. Ironically most of the world's supply comes from the state of Chihuahua in Mexico.
Trade names are used worldwide for many rocks and minerals primarily to boost sales and popularity. Unfortunately they can often be inaccurate and misleading with regards to the geological makeup of the material. Dalmatian jasper is a perfect example. Many colourful or patterned stones that also take on a high polish are often incorrectly labelled as jasper. This is probably because jasper is widely used for decorative purposes so it's a name people are very familiar with.
The dark coloured spots are formed from arfvedsonite although they're often reported to be tourmaline which is not correct. Arfvedsonite is a rare mineral named after the Swedish chemist Johan August Arfwedson who discovered it. Arfwedson is best known for the chemical element lithium which he discovered in 1817.
Weights and sizes of these two dalmatian stones can be found in the adjacent dropdown list. Number 1 is the stone on the left in both photos.