Is the reaction rate always positive? why or why not?

yes the reaction rate is always positive ..
negative sign :
negative sign is always used to show that concentration of reactants is decreasing ..
because of this rate constant is also positive ..
reaction :
if there is negative , than rate constant will be 0 or smaller than zero due to negative sign which means that reaction never occurs so rate of reaction is always positive ..

Idon't know hope someone you

The reaction 2kalsi3o8 + 2(h+ + hco3-) + h2o  →  al2si2o5(oh)4 + 2k+ + 2hco3- + 4sio2 shows that feldspar kalsi3o8 is chemically altered by hydrolysis to form chalky-looking clay mineral kaolinite al2si2o5(oh)4. the chemical breakdown of potassium feldspar due to exposure to acidic water results to the mineral binding with the water molecule to become kaolinite with silica and potassium and bicarbonate ions in solution.