- Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2Si2O5(OH)4) and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite. Shale is characterized by its tendency to split into thin layers (laminae) less than one centimeter in thickness. This property is called fissility. Shale is the most common sedimentary rock.
- A Tour of the Triangulum Galaxy [4K] (youtube.com)
The Milky Way is surrounded by more than 50 near neighbour galaxies that make up the Local Group. The two largest galaxies are us and Andromeda, but we also have an often-overlooked third large galaxy in our neighbourhood- the Triangulum Galaxy. This galaxy is like its own mini-Milky Way, containing stars, clouds, clusters, supernova remnants, and satellites. These are the checkpoints in the Triangulum Galaxy which make up our tour today.
