12 THE MINERALS OF THE MIDLANDS. 



Iron Pyrites is commonly met with iu the clays of the Upper Lias, 

 but is always associated with fossils. I have many large ammonites 

 converted into iron pyrites. Organic matter iu a state of decomposi- 

 tion seems to have the power of reducing the sulphates of sea water, 

 and, in the presence of a ferruginous mud, to give rise to sulphide of 

 iron. No good crystals are found. 



Vivianite (Phosphate of Iron) is met with in very small quantities 

 in the alluvial beds of the Nene, near to Northampton, in the form of 

 small nodules ; also the remains of the horse, deer, ox, wild boar, etc., 

 found there were some of them stained blue by the same material. 



Calcite is commonly met with in the oolitic rocks of Northampton- 

 shire. It occurs iu cracks or cavities of any kind in these rocks, 

 and is often associated with coral. 



Giu^sum or Selenite is of very common occurrence in the clays of 

 the Upper Lias, and the crystals are generally well shaped. 



Mica. — In some few places the Northampton Sand is micaceous. 



Allopliane. — Specimens of a mineral described as Allophane were 

 found near St. Andrew's Hospital, Northampton, by Dr. Berrill, and 

 in an ironstone quarry on the Billing road, near to the above, by Mr. 

 Sharp, F.G.S., F.S.A. After the decease of Dr. Berrill the whole of 

 the material that had been collected was handed over to Mr. Sharp, 

 as well as the following analyses (in Dr. Berrill's writing) : — 



1.— Al^Si^ + lOAq. Allophane. 



2. — Al^Sig + 7Aq. (Dr. Berrill's mineral.) 



3. — Al.,Sig + 4Aq. Kaolin. 



Taking No. 1 as the typical formula of Allophane, and No. 3 of 

 Kaolin, it will be seeu that the mineral is more nearly allied to Kaolin 

 than Allophane. 



NOTTINGHAMSHIRE. 



I am indebted to Mr. A. T. Metcalfe and Mr. John N. Dufty, 

 both Fellows of the Geological Society, for information concerning 

 Gypsum, which appears from their reports to be the only mineral of 

 this county. It occurs at Retford in veins, and is used for garden 

 rock- work. At Southwell thinner veins occur. The mineral occurs, 

 too, at Tuxford, and was formerly used for making plaster floors. 

 " The Geology of the Nottingham District," by the Rev. Alexander 

 Irving, F.G.S., is referred to as bearing slightly on the minerals of the 

 county. 



SHROPSHIRE. 



Professor Prestwich, M. A., F.R.S., refers me to his work, "The 

 Geology of Coalbrook Dale," Trans. Geological Society, 2nd Series, 

 Vol. v., p. 487, and mentions that the following among other minerals 

 are found at Coalbrook Dale : — Thu'iitt'^ (crystals in ironstone), Blende. 

 Iron Plioxplutte, Lead Snlphide, Cnleife, I'etroleiiin, 



