For the quadratic equation \(ax^2 + bx + c = 0\), the discriminant \(\Delta\) is given by:
\[
\Delta = b^2 - 4ac
\]
For the equation \(3x^2 - 2x + \frac{1}{3} = 0\), we have \(a = 3\), \(b = -2\), and \(c = \frac{1}{3}\). Substituting these values into the discriminant formula:
\[
\Delta = (-2)^2 - 4(3)\left(\frac{1}{3}\right)
\]
\[
\Delta = 4 - 4 = 0
\]
Thus, the discriminant is 0. Therefore, the correct answer is option (3).