unknown sedimentary rock

This rock is a combination of numerous fine crystals that cannot be observed with the naked eye or hand lens. However, often times the crystals in other samples can reach medium and large sizes (beyond 0.08 inches (2 mm) and even beyond 0.16 inches (4 mm). In this particular rock the mineral creating it leaves a powdery texture. The rock has a very smooth to slick feel and it's texture is very soft, as evidenced by the scratches shown. The mineral creating this rock has a Moh's hardness scale value of about 2. While this rock displays a dull grey to white color other rocks of this type can be light shades of tan, blue, brown, yellow, pink, and even reddish brown dependent on elements contained. The rock does not contain fossils. This rock doesn't have a salty taste to it. If a drop of acid is placed on the rock surface there is no reaction. Edurock-Educational Virtual Rock Collection CC BY(4.0) via sketchfab [https://creativecommons.org/licenses/by/4.0/legalcode]