There is a type of magnesium brick that is ordinary magnesium chromium brick

Sintered magnesia and fused magnesia with different MgO mass fractions (generally greater than 89%) are combined with refractory grade chromium ore, chromium concentrate, sintered or fused magnesia chromium sand with different Cr₂O₃ mass fractions (sometimes with a small amount of chromium green added) to produce many varieties of magnesium chromium products. 

The most popular varieties of commercial communication nowadays include ordinary magnesium chromium bricks, directly bonded magnesium chromium bricks, combined (semi combined) magnesium chromium bricks, and unburned magnesium chromium bricks.

1. Ordinary magnesium chromium bricks:

Ordinary magnesium chromium bricks are generally produced from sintered magnesia (MgO mass fraction between 89% and 92%) and refractory grade chromium ore. Due to the high content of impurities, the refractory grains are bonded with silicates.

The commonly referred to magnesium chromium bricks in China generally refer to fired ordinary magnesium chromium bricks, also known as silicate bonded magnesium chromium bricks, abbreviated as magnesium chromium bricks.

The production process of ordinary magnesium chromium bricks is simple and the price is cheap, and they are widely used in cement rotary kilns (with Cr₂O₃ mass fraction rarely exceeding 14%), glass kiln regenerators, steelmaking furnace linings, permanent layers of refining steel ladles, non-ferrous metallurgical furnaces, lime kilns, mixed iron furnaces, and high-temperature refractory furnace linings.