A kind of limestone · also called Limestone gravel, Limestone aggregate, Crushed rock

5 views: its portrait, and how it looks in the comparison photos.
About
Crushed limestone is an angular construction rock that packs heavily, weighing about 13.4 ounces (379 grams) per cup.
Crushed limestone has a typical bulk density of roughly 100 pounds per cubic foot (1.6 grams per milliliter). Because machines crush the rock into sharp, irregular pieces, the fragments interlock while leaving small pockets of air between them. A standard five-gallon bucket holds about 67 pounds (30 kilograms) of this aggregate. That makes it noticeably heavier and denser than the same volume of loose dry sand or garden soil.
From Wikipedia
Crushed stone or angular rock is a form of construction aggregate, typically produced by mining a suitable rock deposit and breaking the removed rock down to the desired size using crushers. It is distinct from naturally occurring gravel, which is produced by natural processes of weathering and erosion and typically has a more rounded shape.
Read more on Wikipedia →Text from Wikipedia’s “Crushed stone” article, CC BY-SA 4.0.
4 on the site
One cup weighs
13.4 oz (379 g)
Quick answer
One US cup of crushed limestone weighs about 13.4 ounces (379 grams). That makes it roughly one and a half times as heavy as the same volume of table sugar.
Typical figures, the same ones every comparison on the site uses; real ones vary.
More like crushed limestone
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Next to anything: a person, a car, another limestone.