Realgar (AsS) is a rare and beautiful mineral. Its crystals found in most places on earth are tiny, smaller than 20 mm. One exceptional location is the Realgar Mine at Shimen, Hunan, China. Here is the largest and best Realgar crystal in the world:
R3-01, Realgar, 11.5 x 11.2 x 9.5 cm, $5450 (sold)
Deeply red, strong luster, deep striation on crystal faces. The largest crystal measures 75 x
70 x 30 mm. Location: Realgar Mine, Shimen, Hunan, China
R3-03, Realgar with Calcite, 7 x 4 x 7 cm, $265 (sold) 
Red Realgar crystals, good luster, up to 4 x 2.6 cm large, associate with a nice golden yellow
Calcite crystal on matrix. Location: Realgar Mine, Shimen, Hunan, China