(Born: Beauvais, France, 17 October 1817; Died: Paris, France, 6 May 1897) French mineralogist & crystallographer.

Des Cloizeaux was born into a family with a long tradition in the legal profession. He studied at the Lycée Charlemagne in Paris where he came under the influence of A. Lévy. This association introduced Des Cloizeaux to the study of minerals and crystals, and influenced his attendance of courses on mineralogy taught by A. Brongniart at the Muséum d'Histoire Naturelle and A. Dufrénoy at the École des Mines. A friendship with Jean-Baptiste Biot [1774-1862], gave Des Closieaux the chance to become a member of a government sponsored expedition to Iceland to visit the sources of Iceland spar. During this trip, he visited many English geologists and mineralogists. In 1876, he was made professor of mineralogy at the Muséum, replacing G. Delafosse, who he had assisted since 1873. Des Cloizeaux remained at the Muséum until 1892. He made major studies in the optical properties of minerals, particularly the chondrodites, zoisite and rhombic pyroxenes and amphiboles.

Biographical references: ABF: I 635, 394-398. • Barr, Index to Biographical Fragments, 1973: 51. • Bulletin de la Société Française de Minéralogie: 20 (1897), 167-72 & 259-87, portrait. • Bulletin de la Société Géologique de France: 3rd Series, 25 (1897), 459-60. • Comptes rendus hebdomadaires des séances de l'Académie des sciences: 124 (1897), 983-4. • DSB: 4, 65-7 [by K.L. Taylor]. • Geological Magazine: 35 (1898), no. 10, 480. • Lacroix, A., Notice historique sur François-Sulpice Beudant et Alfred-Louis-Olivier Legrand des Cloiseaux. Membres de la section de Minéralogie. Paris, Académie des Sciences, 1930. 101 p., 2 portraits. • Lacroix, Figures des Savants, 1932-8: 1, 242-72, plates 29-30. • Mineralogical Magazine: 12 (1898), no. 54, 37-8. • Poggendorff: 1, col. 558, 3, 354 & 4, 321. • Proceedings of the Geological Society, London: 1897-8, lii. • Proceedings of the Royal Society of London: 63 (1898), xxv-xxviii. • Sarjeant, Geologists, 1980: 2, 891. • WBI. • World Who's Who in Science: 449.

1. French, 1857 [Dissertation].
N^o D'Ordre 204| Thèses | Présentées | A La Faculté Des Sciences De Paris | Pour Oetenir | Le Grade De Docteur {\`E}s Sciences, | Par M.A. Des Cloizeaux, | [...2 lines of titles and memberships...] | [rule] | I^re Thèse De Minéralogie.-De l'emploi des propriétés | optiques biréfringentes en minéralogie. | II^e Thèse De Chimie.-Propositions données par la Faculté. | [rule] | Soutenues Le Jeudi 28 Mai 1857 Devant La Commission d'Examen. | [rule] | MM. Despretz, Président.| Delafosse, | Desains, Examinateurs. | [ornate rule] | Paris, | Imprimé Par E. Thunot et C^ie, | 26, Rue Racine, 26. | [short rule] | 1857.

4°: 84 p.

Rare. Des Cloizeaux's first major publication was his thesis on the application of the birefringent property of crystals to the determination and classification of mineral species, which he successfully defended in 1857 to obtain his doctorate from the Faculté des Sciences of Paris. In it he advanced a general theory of rotatory polarization. The work was also published as "Mémoire sur l'emploi des propriétés optiques biréfringentes, pour la distinction et la classification des minéraux cristallisés" (Annales des Mines (Paris), 11 (1857), p. 261-342). This was the first in a group of works in which the author explored optical problems in crystallography, and through his methods elucidate ideas about the interior structure of minerals.

Des Cloizeaux continued his research into crystal optics, publishing his results in the Nouvelles Recherches sur les Propriétés Optique des Cristaux, Naturels ou Artificiels, et sur les Variations que ces Propriétés éprouvent sous, Influence de la Chaleur (Paris, 1867).

Bibliographical references: DSB: 4, p. 65-67. • Freund & Berg, Geschichte der Mikroskopie, 1966: 3, p. 163-167. • Lacroix, A., Notice historique sur François-Sulpice Beudant et Alfred-Louis-Olivier Legrand des Cloiseaux. Membres de la section de Minéralogie. Paris, Académie des Sciences, 1930. 101 p., 2 portraits. • Lacroix, Figures des Savants, 1932-8: 1, p. 241-272. • NUC.

Lecons, 1861

2. French, 1861.
[Contained within a double rule box:] Lecons | De | Cristallographie | Professees A L'École Normale, | Par | M. Des Cloizeaux. | [ornament] | Paris, | Mallet-Bachelier, Imprimeur-Libaire | Du Bureau Des Longitudes, De L'École Impériale Polytechnique, | Quai des Augustins, 55. | [rule] | 1861.

4°: [1]-100 p., illus. Title from front wrap.

Rare. Printed from a manuscript holograph, these Lessons on Cristallography were created by Des Cloizeaux for his students at the École Normale. The text provides information about all aspects of the crystallographic science, including definitions, crystal systems, notation, etc.

Bibliographical references: NUC: 140, 293.

3. French, 1862-74 (-1893).
Manuel | De | Minéralogie | Par A. Des Cloizeaux | [...7 lines of titles and memberships...] | [rule] | Tome Premier [-Second] | [rule] | Paris | Dunod, Éditeur, | Libraire Des Corps Impériaux Des Ponts Et Chaussées Et Des Mines, | Quai des Augustins, 49. | [rule] | 1862 [-1874] | Droits de traduction et de reproduction réservés.

2 vols. plus atlas. [Vol 1: 1862] 8°: π² a-c⁸ d² 1-35⁸ 36⁶; 314l.; [4], [i]-l, [2], [1]-572 p., 22 plates (numbered 1-22; nos. 1 & 2 folding). [Vol 2: 1874-93] 8°: π⁸ b-c⁸ d² a⁴ 1-34⁸; 302l.; [i]-lx, [1]-544 p., 20 plates (numbered 23-40; no. 24 folding). Fascile 2 was published in 1893. [Atlas] No title page, 84 plates (numbered I-LXXXIV). Page size: 214 x 130 mm.

Contents: [Vol 1] [2 pgs], Half title page, "Manuel | De | Minéralogie | I.," verso "Paris-Imprimé par E. Thunot et Ce, Rue Racine, 26."; [2 pgs], Title page, verso blank.; [i]-vi, "Préface."-dated March 1862.; [vii]-xlviii, "Introduction."; [xlix]-l, "Errata."; [1 pg], "Manuel | De | Minéralogie."; [1 pg], Blank.; [1]-6, "Incidences des Formes Appartenant au Système Régulier."; [7]-534, "Description des Espèces."; 535-555, "Supplément."; [556], Blank.; [557]-572, "Table Des Matières | Du Premier Volume."

[Vol 2] [i-ii], Half title page, "Manuel | De | Minéralogie | II.," verso "Paris-Imprimerie Arnous De Riviere et Ce, | ..."; [iii-iv], Title page, verso blank.; [v]-viii, "Préface."; [ix]-xlvi, "Additions Et Modifications | Aux Descriptions Du Premier Volume."; [xlvii]-lii, "Additions | A L'Errata Du Premier Volume."; [liii]-liv, "Avant-Propos | Du Second Fascicule."; [lv]-lvii, "Supplement | A L'Errata Du Premier Volume."; [lviii], Blank.; [lix]-lx, "Errata | Du Second Volume."; [1]-528, Text.; [529]-544, "Table Des Matiéres."

[Atlas] Consists of 84 plates, numbered I-LXXXIV, printed on 42 leaves, and showing 514 figures.

Plates: The forty plates contained in the text volumes consist of stereo net projections of various crystal forms of the mineral species. None are signed. The unsigned plates of the atlas are numbered I-LXXXIV. The first shows a polarizing microscope and crystal diagrams, while the remaining plates illustrate crystal drawings of various mineral species described within the text. The plates of the atlas are printed on both sides of the leave.

Rare. An ambitious work that attempts to give a comprehensive view of the internal structure of minerals through the use of optical properties. Des Cloizeaux was an expert practioner in mineral optics, and his original plan had been a simple translation of Henry James Brooke and William Hallowes Miller's edition of William Phillip's An Elementary Introduction to Mineralogy (6th ed., London, 1852). However the project grew much more complex as Des Cloizeaux augmented the text with his own copious observations on the crystallography and optical characteristics of the species. A large portion of this augmentation involved his attempt to firmly establish the optical properties for all known crystalizing minerals. Although the task was to large for him alone to complete, he was able to assemble parameters for over 500 substances, or about half of the mineral species known at the time. In the process, he was conclusively able to show some supposed species to be mere varieties and to discredit many other minerals as identical to species previously described. This research is included in mineralogical descriptions of the Manuel de Minéralogie. For a period, Des Cloizeaux's adoption of the crystallographic notation invented by René Just Haüy and enlarged by Armand Lévy was copied in other French crystallographic works; however, Miller's notation eventually prevailed. Although the author worked on this book for over thirty-five years, this book was never totally completed, with only the two volumes described being published. He was among the first investigators to recognize the utility of the polarizing microscope for mineral analysis.

Fasciles: Contributing to this works scarcety is the fact that it was issued in fasciles. The following list provides the sequence.

Vol. 1, 572 pp., 1862.

Vol. 2, Fascile 1, 208 pp., 1874.

Vol. 2, Fascile 2, pp. 209-544, 1874/93.

Bibliographical references: Dana's 7th (Bibliography): 69. • NUC: 140, 293.

4. French, 1867.
Nouvelles Recherches sur les Propriétés Optique des Cristaux, Naturels ou Artificiels, et sur les Variations que ces Propriétés éprouvent sous, Influence de la Chaleur. Paris, 1867.

4°: [3], [1], 222 p., illus., tables.

Very scarce. This is the last and most comprehensive work in a series of studies Des Cloizeaux published concerning the effect of heat on natural and artificial crystalline bodies. He discovered that sustained heating at a certain temperature would permanently alter the positions of the optic axes of certain crystals (notably the orthoclase minerals), thereby giving the geologist a method to determine if a certain rock had been subjected to high temperature deformation. It was published as, Institute Impérial de France, Mémoires, vol. 18.

Bibliographical references: Dana's 7th (Bibliography): 69. • DSB: 4, 66. • Groth, Entwicklungsgeschichte, 1926: p. 178. • NUC: 140, 293 [ND 0194380].

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