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Darwin Correspondence Project

From William Hallowes Miller   8 March [1845]

8 Park Terrace Cambridge

8 March

My dear Darwin

Pray excuse me for not having sooner given an account of the crystals you sent me—I was busy with lectures and other matters for some time after they came— The cleavage planes are very dull and uneven. I could make nothing of them except by using sun light for the upper signal. The angles usually fell within 15’ of 90o, but different parts of—apparently the same cleavage plane—tho’ in fact cleavage planes of different crystals aggregated together in positions nearly but not quite parallel—differed in position full 15’ not unfrequently. So that I have little doubt of the identity of the crystals with Potash Feldspar1

I regret very much to hear that your health is indifferent. I am well. I have at last been able to escape from College and marry—2 I live in Cambridge where I hope some time to have the pleasure of seeing you

I remain | Dear Darwin | Yours very truly | W H Miller

CD annotations

crossed pencil
1.4 within 15’] underl pencil
crossed pencil


Miller assisted CD by identifying a number of minerals in his South American collections (see South America, pp. 140–1, 153, 154). The description of the Portillo chain in the Chilean Cordilleras refers to pebbles containing crystals of ‘reddish orthitic or potash feldspar (as determined by Professor Miller)’ (South America, p. 182).
Miller married Harriet Susan Minty on 5 November 1844 (Alum. Cantab.).


Discusses cleavage planes of mineralogical specimens.

Letter details

Letter no.
William Hallowes Miller
Charles Robert Darwin
Sent from
Source of text
DAR 39: 42
Physical description
2pp †

Please cite as

Darwin Correspondence Project, “Letter no. 836,” accessed on 17 September 2019,

Also published in The Correspondence of Charles Darwin, vol. 3