Cleavelandite

White, Tan, Blue

Sub-Adamantine, Vitreous, Sub-Vitreous

6 - 6½

2.6

Triclinic

Named in 1823 by Henry J. Brooke in honor of Parker Cleaveland [January 15, 1780 Rowley (Byfield), Massachusetts, USA - August 15, 1858, in Brunswick, Maine, USA], professor of geology and mineralogy at Bowdoin College in Maine 1805-1858. In 1816 Cleaveland wrote the first mineralogy textbook authored by a citizen of the USA. Despite the title page date, the textbook was actually released in January 1817. The textbook was noted for its unification of European schools of thought and was also popular in its second edition of 1822. Cleavelandite had been described earlier in 1817 by Johann Friedrich Ludwig Hausmann with the name "kieselspath". In 1815, Hans Peter Eggertz named granular and radiated albite, probably identical to cleavelandite of Brooke. In 1936, Harold Lattimore Alling defined cleavelandite as a triclinic mineral, suggesting a difference from true albite as well as "analbite". Fisher (1968) studied cleavelandite from Chesterfield, Massachusetts, USA, the type locality, but did not study type specimens, and proposed that true cleavelandite should be restricted to warped platy masses of mineral with lamellae parallel to (010) and "lack other well-defined crystal faces, and may be twinned on the albite law". This definition would not include most specimens called "cleavelandite", especially those cleavelandites grown into open cavities, although such "cleavelandite" is also known from the type locality. The current use of the varietal name generally includes cavity hosted crystal aggregates.

The original annoncement of Cleavelandite was published in Annals of Philosophy, May 1823, p. 381-382:

Article XII. A Description of the Crystalline Form of some new Minerals. By H. J. Brooke, Esq. FRS. FLS. &c. (To the Editor of the Annals of Philosophy.)

Dear SIR, April 19, 1822.
Having lately been engaged in an examination of the crystalline forms of minerals, and in a few instances of their chemical characters, preparatory to a list I have proposed to add to an elementary production to crystallography, I have observed a few new results, which form the substance of the following brief notices: ...
Cleavelandite. - The albite, and siliceous spar of Haussman [sic], which accompanies the green and red tourmaline from Chesterfield, in Massachusetts, are varieties of the same mineral. Two different names having been given to this substance, it becomes necessary either to adopt one of these to the exclusion of the other, or to assign a new one to the species.
As albite is generally blue, and sometimes red,* its name is consequently bad, and siliceous spar might be applied with equal propriety to the other substances; I have therefore, preferred adopting the term Cleavelandite to denote the species, out of respect to the Professor of Natural Philosophy in Bowdoin College. United States.
This species has cleavages in three directions, parallel to the planes of a doubly oblique prism.

* The specimen which first enabled me to determine the form is bright blue. It came from Labrador, and was given to me by the Rev. C. I. Latrobe. M. Nordenskiold has favored me with a specimen which is red.

ⓘ Clark Ledge pegmatite locality, Chesterfield, Hampshire County, Massachusetts, USA