6o THE BUII.DIXG OF AN ISLAND. 



Hornhle7ide is a dark-coloured, glistening mineral, very common in the 

 older rocks. Professor Cleve remarks that large crystalline masses are found 

 near Santa Cruz in the small Green Cay. 



Mica is a mineral that crystallizes in tliin sheets, which in some countries 

 are sufficiently large and transparent to form to some extent a substitute for 

 glass. In our own island the mineral is found in tinv flat specks disseminated 

 through some of the rocks, as, for example, near Grange and Beeston Hill and 

 near Hermitage. In some places it has been sorted out from the other mate- 

 rials by the running streams, and may be collected in some quantity. Many 

 years ago the writer was shown a sample of such mica sand, which, on account 

 of its yellow, shiny appearance, had been sent to a London assaver for examin- 

 ation, and was jironounced by him to contain gold, but in too small proportion 

 to make the sand of any value. 



Magnetic Iron Ore. On the sand of the shore near Fair Plain a black sand 

 may sometimes be seen in patches, and on examination of the particles thev 

 proved to be small crystals of magnetic iron ore. Here it is the motion of the 

 v^'^aves on the beach which sorts out the iron grains in this peculiar manner ; 

 but like the grains of mica sand, these particles have been derived from decom- 

 posed rocks of the Indurated Clay formation, and have been brought down by 

 the streams. This is a mineral which is found in many parts of the world, and 

 in some places is very abundant. As is well known, Mr. Edison has large 

 works in New Jersey for crushing certain rocks which are abundant there and 

 for separating the iron grains by sets of powerful electro-magnets, in front of 

 which the powdered rock is dropped in a continuous stream, the iron grains 

 being drawn inwards as they pass the magnets and so falling in a separate heap. 

 Afterwards the material is made into bricks for transportation to the iron 

 works where it is to be manufactured. 



The minerals to which attention has been drawn in the above notes are 

 those which will commonly be noticed by the amateur while examining the 

 rocks of St. Croix. 



So far as is known to the present writer, no valuable ores occur in the 

 island, which is not the same thing, however, as saying that there are none. 

 The writer, to say nothing of the rock exposures which he has not examined, is 

 not a mineralogist, and it is possible that he may have passed by some indica- 

 tions that may be recognized by an expert later. Molybdena and ores of 

 copper are found in the neighbouring island of Virgin Gorda, and the writer 

 has been told that galena (lead ore) containing traces of gold and silver has 

 been found in one of the St. Thomas Cays. Gold is also occasionally found in 

 the beds of some of the Porto Rico streams. With all these indications in the 

 neighbourhood, it may well be that some valuable metallic ores occur in St. 

 Croix. If ever found, the question will still remain whether they are worth 

 anything from a commercial point of view, a question which in the instances 

 named has been so far answered in the negative. 



