Marble is a rock resulting from metamorphism of sedimentary carbonate rocks, most commonly limestone or dolomite rock.
Metamorphism causes variable recrystallization of the original carbonate mineral grains. The resulting marble rock is typically
composed of an interlocking mosaic of carbonate crystals. Primary sedimentary textures and structures of the original carbonate rock (protolith)
have typically been modified or destroyed.

Onyx is a cryptocrystalline form of quartz.
The colors of its bands range from white to almost every color (save some shades, such as Purple or Blue).
Commonly, specimens of onyx available contain bands of colors of white, tan, and brown.
Sardonyx is a variant in which the colored bands are sard (shades of red) rather than black.
Pure black Onyx is common, and perhaps the most famous variety, but not as common as Onyx with banded colors.

More marble dice can be seen in DICE from PERU

[0369 x3] Small marble dice bought in Luxor, 13 mm

[0416 x2] Marble dice from Italy, 16 mm

[0574] Large marble dice from KrK, Slovenia, 55 mm

[0737] Large marble die from Crete, 43 mm

[0768] A huge (1.16 kg) green dice made out of marble from Carrara in Toscany, Italy, 77 mm

[0793] A large heavy 'play card' dice, marble, 51 mm

[0794] Large black marble dice, Pakistan, 37 and 33 mm

[0820] A pair of small onyx dice, Pakistan, 19 mm

[1104] A marble dice bought in Mexico and probably made elsewhere in South America, 21 mm

[1244 x3] 3 large marble dice, Pakistan, 52, 52, 54 mm

[1256] Marble die, 27 mm

[1257] Large marble die, 41.5 mm

[1258] Small marble die bought in Canada, 1,2 in black, 3,4,5,6 in red, 15 mm

[1259] Small black marble die, 14 mm

[1260 x2] Pair of large marble dice, 39 mm