64 
Proceedings of the Royal Society 
faction, in name of the Council of this Society, of presenting you 
with the Keith Medal. It is hoped that this recognition of your 
labours will not be without encouragement to you in the arduous 
researches in which you are engaged. 
The following Gentlemen have been recommended by the 
Council to fill the vacancies in Foreign Honorary Fellowships 
caused by the deaths of Claude Bernard, Elias Magnus Fries, 
Henri Victor Regnault, Angelo Secchi : — 
Frank Cornelius Donders, Utrecht. 
Asa Gray, Cambridge, U.S. 
Jules Janssen, Paris. 
Johann Benedict Listing, Gottingen. 
The following Communications were read : — 
1. Chapters on the Mineralogy of Scotland. By 
Professor Heddle. Chapter V. 
(Abstract.) 
In this chapter Dr Heddle considered the micas occurring in 
Scotland. These he found to be Muscovite or Muscovy glass, and 
margarodite — of the white micas; Biotite, lepidomelane, and a new 
species which he proposes to call Haughtonite, after Professor 
Haughton of Dublin — of the dark micas. He also finds the species 
pihlite, hitherto unrecognised in Britain, occurring in quantity 
in the central districts of Banffshire, and in the west of Aber- 
deenshire. 
In connection with the first of these micas, the mode of formation 
of exfiltration veins, and the metamorphism of gneiss into the grey 
granite of Aberdeenshire, were considered. 
Dr Heddle found that margarodite is the glistening constituent of 
all the so-called talc slates which he had analysed ; he doubts the 
occurrence of the last-named rock $n Scotland, as no one of the rocks 
which he has examined, and which have passed by that name, was 
found to contain any talc. 
Biotite in Scotland is characteristic of granular limestones, which 
also rarely contain margarodite. Lepidomelane, the ordinary 
dark-granite mica of Ireland, he had found in Scotland in only 
two localities. 
