Babingtonite
Introduction

**Babingtonite** is a [calcium](/wiki/Calcium "Calcium") [iron](/wiki/Iron "Iron") [manganese](/wiki/Manganese "Manganese") [inosilicate](/wiki/Silicate_minerals "Silicate minerals") mineral with the formula . It is unusual in that iron(III) completely replaces the aluminium so typical of silicate minerals. It is a very dark green to black translucent (in thin crystals or splinters) mineral crystallizing in the [triclinic](/wiki/Triclinic "Triclinic") system with typically radial short prismatic clusters and [druzy](/wiki/Druse_%28geology%29 "Druse (geology)") coatings. It occurs with [zeolite](/wiki/Zeolite "Zeolite") minerals in cavities in [volcanic rocks](/wiki/Volcanic_rock "Volcanic rock"). Babingtonite contains both iron(II) and iron(III) and shows weak [magnetism](/wiki/Magnetism "Magnetism"). It has a [Mohs hardness](/wiki/Mohs_hardness "Mohs hardness") of 5\.5 to 6 and a [specific gravity](/wiki/Specific_gravity "Specific gravity") of 3\.3\.

It was first described in 1824 from samples from [Arendal](/wiki/Arendal "Arendal"), [Aust\-Agder](/wiki/Aust-Agder "Aust-Agder"), [Norway](/wiki/Norway "Norway") (which is its [type locality](/wiki/Type_locality_%28geology%29 "Type locality (geology)")) and was named after the [Irish](/wiki/Ireland "Ireland") [physician](/wiki/Physician "Physician") and [mineralogist](/wiki/Mineralogist "Mineralogist") [William Babington](/wiki/William_Babington_%28physician%29 "William Babington (physician)") (1757–1833\).

It is the official mineral (mineral emblem) of the [Commonwealth of Massachusetts](/wiki/List_of_Massachusetts_state_symbols "List of Massachusetts state symbols").[Massachusetts: Mineral or mineral emblem of commonwealth](http://www.mass.gov/legis/laws/mgl/2-18.htm) The first published report of babingtonite in Massachusetts was by Francis Alger in 1844 The first published report of babingtonite in Massachusetts was by [Francis Alger](/wiki/Francis_Alger "Francis Alger") in 1844,Phillips, W., Allan, R., and Alger, F. (1844\) An Elementary Treatise on Mineralogy, 5th ed. (Boston: W. D. Ticknor \& Co.) who credited [Thomas Nuttall](/wiki/Thomas_Nuttall "Thomas Nuttall") with its discovery in Charlestown (now Somerville). The location was the Granite Street quarry, formerly known as the Milk Row quarry.


What is babingtonite?