You think probable to talc.
Talk Graphite
The mineral that is soft and metallic is talc. Talc is known for its greasy feel and can be easily scratched with a fingernail, making it one of the softer minerals on the Mohs scale.
The mineral that is flat with flaky cleavage is mica. Mica is a group of silicate minerals that can easily be split into thin sheets or flakes. These sheets have excellent cleavage, making them easily separable into thin layers.
Mica
graphite
Calcite
The soft silicate flakes found in many rocks are likely to be mica minerals, such as muscovite or biotite. These minerals have a layered structure that allows them to break into thin flakes or sheets easily. Mica minerals are common in igneous, metamorphic, and sedimentary rocks.
Calcite is a non silicate mineral because it does not contain silicon.
Wulfenite has a mineral hardness of 3-3.5 on the Mohs scale, which means it is relatively soft and can be easily scratched by harder materials.
The mineral you are referring to is likely gypsum. Gypsum is a soft, colorless to light-colored mineral that can appear translucent and has good cleavage.
it is not hard because you can split the mineral
The flaky dark mineral commonly found in granite is biotite. Biotite is a mica mineral that typically appears as black or dark brown flakes and is characterized by its perfect cleavage, allowing it to be easily split into thin sheets. It contributes to the overall texture and mineral composition of granite, alongside quartz and feldspar.