Earth & SkyGreek → English
Microcline
/ˈmaɪkrəklaɪn/noun
A potassium feldspar whose cleavage angle falls just short of ninety degrees.
The Greek roots
μικρός
mikrós
small
κλίνειν
klínein
to lean, to slope
Literally: “slightly leaning”
The story of the word
Breithaupt named it in 1830 for a very small deviation: the cleavage misses the right angle by about twenty minutes of arc. That fraction of a degree is most of what separates it from orthoclase, which has the same chemistry and forms at higher temperatures. The blue-green variety, amazonite, is the one that ends up cut and set in silver.
- How it travelled
- Ancient Greek → German → English
- First recorded
- 19th century
Same family
orthoclaseplagioclasemicroscopeclimate
In a sentence
The pegmatite is mostly quartz and microcline.
Under crossed polars the microcline showed its cross-hatched twinning.