Aloha Michael,
Absolutely this is a non-slip floor.
Any type of mosaic will usually be non-slip due to it's small size and larger area of grout, which is usually non-sanded.
There are many porcelain tiles that have a higher slip co-efficient and may be safely used in showers. Also, look at commercial floor tiles as they are designed for safety in public areas. You can cut them to the size you prefer.
We once installed a black quartzite floor in a shower and had it brushed by the granite fabricator. What was really interesting about doing this technique to the tile is that when it was dry, it felt like it had a small amount of traction. But, when it was wet it had a lot of traction and was perfect for a safe shower.
We have also applied 511 stone sealer which has something in it that adds traction. This would only be appropriate for natural stone.
Hope that helps!