Brown sugar usually refers to the finished sugar of sugar cane with honey, and generally refers to the honey formed after sugar cane is squeezed, simply treated and concentrated. Brown sugar is divided into brown sugar, brown sugar powder and bowl sugar. According to the different crystal particles, almost all the components in sugarcane juice are retained because they are not highly refined. Besides the function of sugar, it also contains vitamins and trace elements, such as iron, zinc, manganese and chromium. And the nutrients are much higher than sugar.
So it is not an impurity.