Namesake Minerals #10

Happy New Year everyone! 2017 is finally here as well as the return of fortnightly namesake minerals posts! It’s been quite a while since the last post so today you’ll be treated to three minerals named after famous petrographers.

Deerite, howieite and zussmanite were first discovered in Laytonville Quarry (pictured above). This quarry contains glaucophane schists from the Franciscan Formation. The rocks here consist of Jurassic/Cretaceous volcanic rocks and metamorphosed chert, shale, ironstone and limestone. They were formed from oceanic crust which experienced high pressure, low temperature metamorphism during subduction. As this crust became hydrated, deerite formed in ironstones and zussmanite formed in iron-rich, manganese-poor pelites. After the pressure dropped, howieite developed along with a manganese-rich variety of zussmanite.



Black, bladed crystals of deerite with quartz and riebeckite, from Laytonville Quarry, California, USA (image from

Quick facts:

  • Silicate mineral
  • Found in metamorphosed ironstones (blueschist facies) and copper/iron sulphide deposits
  • Type locality: Laytonville Quarry, Mendocino County, California, USA
  • Formula: (Fe,Mn)6(Fe,Al)3(Si6O17)O3(OH)5
  • Crystal system: Monoclinic
  • Hardness: 6
  • Density: 3.837g/cm3

Deerite was first discovered in 1964 in Laytonville Quarry. There are occurrences throughout California and countries such as Greece, Italy and Turkey but it’s a rare mineral. It’s commonly associated with howieite, zussmanite, stilpnomelane, spessartine, riebeckite and quartz.



Howieite crystals associated with quartz and siderite, from Laytonville Quarry, California, USA (image from

Quick facts:

  • Silicate mineral
  • Found in metamorphosed shales, siliceous ironstones and impure limestones
  • Type locality: Laytonville Quarry, Mendocino County, California, USA
  • Formula: Na(Fe,Mn)10(Fe,Al)2Si12O31(OH)13
  • Crystal system: Triclinic
  • Hardness: undetermined
  • Density: 3.378g/cm3

Howieite has a bladed or radiating habit and looks similar to deerite. Even though this mineral was discovered over 50 years ago, its hardness remains undetermined.


pale zussmanite.jpg

Tabular zussmanite crystals from Laytonville Quarry, California, USA (image from

Quick facts:

  • Silicate mineral
  • Found in metamorphosed shales, siliceous ironstones and impure limestones
  • Type locality: Laytonville Quarry, Mendocino County, California, USA
  • Formula: K(Fe,Mg,Mn)13(Si,Al)18O42(OH)14
  • Crystal system: Trigonal
  • Hardness: undetermined
  • Density: 3.146g/cm3

Green variety of zussmanite, from Laytonville Quarry, California, USA (image by Jesse Crawford from

Zussmanite has a layered structure similar to mica and its colour ranges from light to dark green.Unlike the other two minerals, zussmanite has only been found at Laytonville Quarry. It has been suggested that this mineral is formed during the metamorphism of deep ocean sediments in the blueschist facies.




All three of these minerals were named in 1964 by Stuart Olof Agrell, Michael G. Brown and Duncan McKie in honour of three prominent mineralogists. Here are their stories…



William Deer (image from

William Alexander Deer was born in Manchester on 26th October 1910. During his childhood, he was inspired by Darwin’s Origin of Species. He studied at the University of Manchester and later secured a research studentship at St. John’s College, Cambridge.

Between 1935-1936, he went on an expedition to Skaergaard in Greenland with Laurence Wager. The pair mapped an area covering 35,000km2 which included the famous Skaergaard Intrusion. A memoir of their research was published in 1939 and this was the first quantitative study of a layered intrusion. The outbreak of World War Two interrupted the research but Deer managed to return to Skaergaard in 1953 and 1966. He collected 380m of core which has been used in various scientific papers.

In 1950, he became a professor at the University of Manchester and changed a tiny department into a top rate School of Geology; the department had the first hydrothermal high pressure experimental laboratory in Britain. Eleven years later he moved to Cambridge and became a professor of Mineralogy and Petrology at the university and was later appointed Vice Chancellor for four years in 1971.

Deer also had many achievements outside of university life. He served as the president of both the Mineralogical Society and Geological Society, was a Trustee of the Natural History Museum and a member of the Natural Environment Research Council. The Geological Society awarded him the Murchison Fund and Murchison Medal in 1946 and 1974 respectively. He received a Fellowship of the Royal Society in 1962 and an Honorary DSc from the University of Aberdeen in 1984.

Deer had three children with his first wife Margaret Kidd (married in 1938). After her death in 1971, he married Rita Tagg in 1973. He died on 8th February 2009.



Robert Howie (image from

Robert Andrew Howie was born on 4th June 1923 in Buckinghamshire, England. In his late teens, he volunteered for the RAF in Gibraltar but after contracting poliomyeltis, his mobility was affected.

He graduated from Trinity College, Cambridge in 1950 with a degree in Chemistry, Geology and Mineralogy. A few years later, Howie completed his PhD on charnockite which is a dark granite. His analyses proved that this rock has an igneous origin rather than the metamorphic origin which was originally proposed. A year later he became a lecturer at Manchester University where he met Deer and Zussman. In 1986, he became a reader in geology and then a professor at Royal Holloway, University of London.

Howie has 50 published papers on topics such as silicate mineralogy, pyroxene, amphiboles, tourmaline and axinites. From 1971 to 2003, he was the principle editor of Mineralogical Abstracts and wrote over 1600 abstracts per year. His awards include the Murchison Medal from the Geological Society in 1976 and the Public Service Award from the Mineralogical Society of America in 1999. Howie died on 10th March 2012.


Jack Zussman, the only surviving member of the trio, was born in 1924 and is currently a professor at the University of Manchester.


The trio wrote a multi-volume encyclopaedia called ‘Rock Forming Minerals’. The first edition contained five volumes and was published in 1962. Another edition was published in 1978 and the most recent edition consists of 11 volumes. A condensed student edition called ‘An Introduction to the Rock Forming Minerals’ was published in 1966. This book is usually part of the required reading in many geology undergraduate degrees.


Left: First edition from 1966 (image from Right: Third edition from 2013 (image from


Header image from


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s