In the form of what compounds do the metals potassium, magnesium, chromium and zinc

In the form of what compounds do the metals potassium, magnesium, chromium and zinc occur in nature? Write down the chemical formulas for these compounds.

Magnesium is predominantly found in seawater – Mg 0.12-0.13%
The main types of magnesia raw materials:
– carnallite – MgCl2 • KCl • 6H2O (Mg 8.7%)
– bischofite – MgCl2 • 6H2O (Mg 11.9%),
– kieserite – MgSO4 • H2O (Mg 17.6%),
– epsomite – MgSO4 • 7H2O (Mg 16.3%),
– brucite – Mg (OH) 2 (Mg 41.6%).

Potassium is found in the earth’s crust and is 1.84%. Such compounds are known:
– KCl – sylvin
– NaCl KCL-sylvinite
– K₂CO₃ – potash
– KCl MgCl₂ 6H₂O -carnallite

Sphalerite is a zinc mineral. Varieties:
– ZnS zinc blende
– ZnO – zincite
– ZnCO₃ -galmey