Granite containing orthoclase felspar produces a fairly fertile soil.    From Wordnik.com.  [Manures and the principles of manuring] Reference

Other kinds of felspar, even orthoclase, may however also show the aventurine appearance.    From Wordnik.com.  [Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 1 "Austria, Lower" to "Bacon"] Reference

The minerals included in this group are orthoclase, microcline, and the plagioclase feldspars.    From Wordnik.com.  [Feldspar] Reference

(K2O · Al2O3 ·6SiO2), exists as minerals named orthoclase and microcline, melting at 1200°C.    From Wordnik.com.  [13. Glaze oxides] Reference

This change may be illustrated by quoting the analysis of a kaolin clay formed by the disintegration of orthoclase felspar.    From Wordnik.com.  [Manures and the principles of manuring] Reference

Those yielded by orthoclase must generally abound in potash, while albite and labradorite, containing little or none of that element, must produce soils in which it is deficient.    From Wordnik.com.  [Elements of Agricultural Chemistry] Reference

It must be remembered, however, that it is only the orthoclase or potash felspars which contain large quantities of potash -- other felspathic rocks, such as oligoclase and labradorite, being comparatively poor in it.    From Wordnik.com.  [Manures and the principles of manuring] Reference

It stands to reason that as the presence of potash in a soil is one of the distinguishing features of its fertility, much will depend on the extent to which the orthoclase felspar is present; and also, not only on the extent, but on the state and degree of its disintegration.    From Wordnik.com.  [Manures and the principles of manuring] Reference

There are, for instance, several different minerals commonly classified under the name of felspar, which have been distinguished by mineralogists by the names of orthoclase, albite, oligoclase, and labradorite; and there are at least two sorts of mica, two of hornblende, and many varieties of zeolites.    From Wordnik.com.  [Elements of Agricultural Chemistry] Reference

The minerals anorthite, albite, and orthoclase named in this figure are all feldspars; sylvite and halite are chlorides of potash and soda.    From Wordnik.com.  [The Economic Aspect of Geology] Reference

He keeps collections of local minerals for sale, among which the orthoclase crystals struck us as being extraordinarily large and beautiful.    From Wordnik.com.  [Untrodden Peaks and Unfrequented Valleys] Reference

The mineral orthoclase, which enters largely into the constitution of many granites, was found to lose under the same conditions 0.025 gramme.    From Wordnik.com.  [The Birth-Time of the World and Other Scientific Essays] Reference

A soft extremely fine grained gray rock, with a well developed schistose structure, carrying much magnetite, plagioclase, orthoclase and their alteration products.    From Wordnik.com.  [The Long Labrador Trail] Reference

Perhaps 75\% of this is the plagioclase feldspars (mostly albite, oligoclase and labradorite) with the remainder as potassium feldspars (mostly microcline and orthoclase).    From Wordnik.com.  [Netvouz - new bookmarks] Reference

Alteration in the vicinity of the well mineralized samples is dominantly potassic and characterized by the presence of fine masses of orthoclase feldspar and secondary biotite within large intrusive talus blocks and narrow veins cross cutting the overlying volcanic sequence.    From Wordnik.com.  [Marketwire - Breaking News Releases] Reference

3. 0-3.1 orthoclase.    From Wordnik.com.  [Chapter 6] Reference