6 robots in the mine

FCFS:

Moment 1
	wheelbarrow arrived <1 gold 2 1 [2]>
	wheelbarrow arrived <2 rubins 3 2 [6]>
	wheelbarrow arrived <3 coconuts 3 1 [3]>
	wheelbarrow arrived <4 turquoise 1 2 [2]>
		[gold        2][rubins      6][coconuts    3][turquoise   2][             ][             ]
Moment 2
		[gold        1][rubins      5][coconuts    2][turquoise   1][             ][             ]
Moment 3
	wheelbarrow arrived <5 aventurines 3 2 [6]>
	wheelbarrow arrived <6 beryls 2 1 [2]>
		[aventurines  6][rubins      4][coconuts    1][beryls      2][             ][             ]
Moment 4
	wheelbarrow arrived <8 sapphires 4 2 [8]>
	wheelbarrow arrived <9 emeralds 1 1 [1]>
	wheelbarrow arrived <10 opals 4 3 [12]>
	wheelbarrow arrived <11 gold 1 1 [1]>
	wheelbarrow arrived <12 amethysts 3 4 [12]>
		[aventurines  5][rubins      3][sapphires   8][beryls      1][emeralds    1][opals      12]
Moment 5
		[aventurines  4][rubins      2][sapphires   7][gold        1][amethysts  12][opals      11]
Moment 6
	wheelbarrow arrived <13 topazes 2 1 [2]>
	wheelbarrow arrived <14 pearls 3 4 [12]>
	wheelbarrow arrived <15 gold 2 1 [2]>
	wheelbarrow arrived <16 aquamarines 2 1 [2]>
		[aventurines  3][rubins      1][sapphires   6][topazes     2][amethysts  11][opals      10]
Moment 7
		[aventurines  2][pearls     12][sapphires   5][topazes     1][amethysts  10][opals       9]
Moment 8
		[aventurines  1][pearls     11][sapphires   4][gold        2][amethysts   9][opals       8]
Moment 9
		[aquamarines  2][pearls     10][sapphires   3][gold        1][amethysts   8][opals       7]
Moment 10
		[aquamarines  1][pearls      9][sapphires   2][             ][amethysts   7][opals       6]
Moment 11
		[             ][pearls      8][sapphires   1][             ][amethysts   6][opals       5]
Moment 12
		[             ][pearls      7][             ][             ][amethysts   5][opals       4]
Moment 13
		[             ][pearls      6][             ][             ][amethysts   4][opals       3]
Moment 14
		[             ][pearls      5][             ][             ][amethysts   3][opals       2]
Moment 15
		[             ][pearls      4][             ][             ][amethysts   2][opals       1]
Moment 16
		[             ][pearls      3][             ][             ][amethysts   1][             ]
Moment 17
		[             ][pearls      2][             ][             ][             ][             ]
Moment 18
		[             ][pearls      1][             ][             ][             ][             ]
OK