The pumice-tuffs of Mount Thuku are non-calcareous, and exhibit greyish pumiceous lapilli in an abundant white matrix formed of fine pumice-debris.
The puzzling little white patches so common in basic tuffs merely represent lapilli of basic pumice that have been palagonitised, and then bleached and disintegrated by hydration.
Some of the beds contain a number of lapilli of basic pumice, 1 to 3 centimetres in size, which are often in the last stage of the disintegration produced during palagonitisation.
In it occur pumiceous lapilli of the same material up to 2 centimetres in diameter.
Stout crystals of augite can be picked out of it, and it contains also lapilli up to an inch in size of a basic vesicular semi-vitreous basalt.
In those cases where lapilli of altered basic pumice occur in the deposit, sub-aerial eruptions are directly indicated.
They may be uniform in structure, or they may display thin seams of a marl-like clay, or they may contain numerous lapilli of vesicular basic glass extensively palagonitised.
The matrix is made up of fine detritus of the large fragments and of lapilli of a vacuolar palagonitic basic glass, whilst small crystals of calcite fill the cavities and line the fissures.
In the case of the volcano which we are studying, the lapilli are so black that they give the cone the appearance of being darkened by the shadow of a cloud, and on this account the peak is named Shadow Mountain.
The lapilli and scoriæ are slag-like fragments of lava which have been blown out of the throat of the volcano while in a hot or semi-molten condition.
The mountain, throughout its height of over one thousand feet, is a conical aggregate of loose lapilli which give way under the feet and make climbing the peak very tiresome.
Even before we reached the pine-forest there was evidence of the action of water, which had covered the slope of the mountain with beds of thick compact tufa, composed of these lapilli mixed with fragments of lava.
The black tin-stone, lapilli nigri has been treated in a similar manner, lapilli (small stones) constantly occurring alone in the Latin.
The lapilli and the ashes were carried to greater distances.
Smoke and hydrochloric acid issued from the aperture in its envelope, and being partly broken it was seen to contain lapilli and pieces of antecedent lava, covered with micaceous peroxide of iron.
A small fusillade may go on for months, and yet, without an hour's notice, by any premonitory sign, may waken up to a roar and darken the air with ashes and lapilli such as those which overwhelmed Pompeii.
These ejections were followed by dark sand, with lapilli and small fragments of scoriae of the same colour.
A great quantity of coleoptera assembled on the flat roof of the Observatory, where the ashes and lapilli were heaped up two decimetres in height.
That those lapilli and the pieces of lava were solid when enveloped in the paste of the new lava, we infer from seeing the impressions on the inside of the said envelope.
The great quantity of lapilli which fell buried the scoriae with which the Vesuvius cone was covered, so that it became somewhat more difficult to ascend to the summit, and much less difficult to descend.
Coming now to Ice Springs Craters in Utah, we find here three small craters formed of scoriae and lapilli (volcanic ashes consisting of small angular stony fragments).
It was seen in operation, throwing up steam, clots of lava, and lapilli (some of the larger pieces of fragmentary lava) in the year 1878.
We observed, that when lava abounded, the projection of rocks and lapilli either ceased altogether, or became of small amount.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "lapilli" in a variety of sentences. We hope that you will now be able to make sentences using this word.
