176 MANGANESE DEPOSITS OF INDIA : MINERALOGY. [ PaRT I : 
darker, being occasionally almost blood-red. In one case at Hatora 
T foimd a specimen shoAving a layer of this garnet resting on manganese- 
ore. The spessartite was of a colour that almost exactly matched 
that of crystals of potassium bichromate. Of the colours mentioned 
above the pure orange and the guava- jelly colour are about equally 
common, there being of course every gradation from one into the other. 
When the crystals are darkened due to alteration, the result is usually 
to give rise to deep reddish black colours, as in the crystal of garnet 
from Chargaon shown in figure 14. This is simply the result of the 
darkening of the true orange or orange-red of the unaltered mineral, 
owing to the presence in it of black oxides of manganese. Such crystals 
when boiled in hydrochloric acid so as to remove the oxides often assume a 
bright orange colour. Sometimes, however, the colour is a dark chocolate- 
brown due to the fact that the mineral has become very much altered 
throughout its substance ; when it has reached this condition the garnet 
is usually fairly soft and easily scratched with a knife. Occasionally large 
crystals are yeUow in colour, as at Satak ; this is not, however, the colour 
seen through a good thickness of the transparent mineral, but only that 
seen through a small thickness at the surface, the underlying portions 
being altered. Since an orange mineral when seen in thin layers 
would appear to be yellow, it is probable that if this example from 
Satak were fresh and unaltered, so that one could look into it through a 
good thickness of the mineral, it would also appear to be of an orange or 
orange-red coloiir. The colours as given above are only those 
observed on crystals large enough to handle conveniently, i.e., not 
smaller than \ inch in diameter. But as seen in the fine-grained rocks 
containing this mineral the colour is often much paler, such as sulphur- 
yellow, pale yellow, cinnamon, and even grejnsh. Under the micro, 
scope also there is seen to be a great variation in the colour of spessartite. 
I should say that the most characteristic colour as seen thus is a Ught 
yellow ; but sometimes the colour is as dark as bright sulphur- yellow, or 
so pale that the mineral is practically colourless, although the latter 
form is rare. In rarer cases the mineral shows some shade of brown 
in the yellow, and occasionally the colour is sufficiently dark to be 
called light orange. In very rare cases the mineral shows a distinct 
pink tint, but in such a case it may perhaps be doubted if the mineral 
ifi truely to be regarded as spessartite. A case in point is that of a 
manganese-garnet in gondite from Bichua. In the hand-specimen the 
mineral is of an orange -red colour, whilst under the microscope it is a 
sakQon-pink. 
