Origin of Ironstone. 
117 
Nature's universal dye. Without it the soil would be 
a dirty white — the colour of snow in the time of 
thaw. Instead of the pretty , lively colour of sand and 
pebbles, we should see the dull and sombre hue of 
ashes, and, instead of the glittering sand of the sea 
and lake-shore, a plain drab or gray, which no wealth 
of sunshine or of spray could turn to beauty. The 
slates used for roofing have a warm, rich tint; oxide 
of iron puts vermilion into them, as it does into our 
bricks, which else would be only a plain pepper and 
salt. The ruddy hues of brown now seen in plough- 
ing sandy fields, contrasting so richly with the green 
of woods and meadow, would be, without the iron, 
only the cold repulsive gray of clayey soils. Many 
marbles, too, are coloured with the same familiar dye. 
The violet veinings and variegations of the marble of 
Sicily and Spain, the glowing orange and amber of 
Sienna, the blood-red colour of precious jasper that 
enriches the temples of Italy, are all painted with 
iron-rust." 
The actual amount of iron, however, present in 
even highly-coloured rocks is so small indeed that it 
could never be extracted with profit. It is only when 
ironstones are concentrated, as it were, in beds, veins, 
and lodes that the ore is rich enough to pay for the 
extraction of metallic iron. 
How comes it that, as in the case of the Hawkes- 
bury Sandstones, the ironstones occur in beds ? Why 
is it that a considerable thickness of Wianamatta 
Shales should be practically devoid of iron, while 
