Question: What synthetic stimulant is sometimes called flaka or gravel?

Context paragraphs:
Kesterite: Kesterite is a sulfide mineral with a formula Cu(Zn,Fe)SnS.  In its lattice structure, zinc and iron atoms share the same lattice sites.  Kesterite is the Zn-rich variety whereas the Zn-poor form is called ferrokesterite or stannite.  Owing to their similarity, kesterite is sometimes called isostannite.  The synthetic form of kesterite is abbreviated as CZTS (from copper zinc tin sulfide).  The name kesterite is sometimes extended to include this synthetic material and also CZTSe, which contains selenium instead of sulfur.

Road roller: A road roller (sometimes called a "roller-compactor", or just "roller") is a compactor type engineering vehicle used to compact soil, gravel, concrete, or asphalt in the construction of roads and foundations.  Similar rollers are used also at landfills or in agriculture.

Xenoestrogen: Xenoestrogens are a type of xenohormone that imitates estrogen.  They can be either synthetic or natural chemical compounds. Synthetic xenoestrogens are widely used industrial compounds, such as PCBs, BPA, and phthalates, which have estrogenic effects on a living organism even though they differ chemically from the estrogenic substances produced internally by the endocrine system of any organism.  Natural xenoestrogens include phytoestrogens which are plant-derived xenoestrogens.  Because the primary route of exposure to these compounds is by consumption of phytoestrogenic plants, they are sometimes called "dietary estrogens".  Mycoestrogens, estrogenic substances from fungi, are another type of xenoestrogen that are also considered mycotoxins.

Chalicosis: Chalicosis (Greek, χάλιξ, gravel), sometimes called flint disease, is a form of pneumoconiosis affecting the lungs or bronchioles, found chiefly among stonecutters.

Methcathinone: Methcathinone (α-methylamino-propiophenone or ephedrone) (sometimes called "cat" or "jeff" or "catnip" or "intash" ) is a monoamine alkaloid and psychoactive stimulant, a substituted cathinone.  It is used as a recreational drug due to its potent stimulant and euphoric effects and is considered to be addictive, with both physical and psychological withdrawal occurring if its use is discontinued after prolonged or high-dosage administration.  It is usually snorted, but can be smoked, injected, or taken orally.

Guaraná Jesus: Guaraná Jesus is a Brazilian soft drink produced by Eduardo Lago, a Coca-Cola bottler based in São Luís.  The drink is popular within the region, reportedly outselling Coca-Cola, and is made from extracts of the guarana plant, which contains caffeine (sometimes called "guaranine"), theophylline, and theobromine.  Lago has noted that "Every Brazilian knows that guarana is a stimulant and that means it stimulates everything".  The drink is named for Jesus Norberto Gomes, the druggist who formulated the drink in 1920.  The drink has a pink color, a cinnamon aroma and a very sweet taste, and is marketed with the slogan "the pink dream".  The drink is now a brand owned by the Coca-Cola Company.

Synthetic ice: Synthetic ice is a solid polymer material designed for skating using normal metal-bladed ice skates.  Rinks are constructed by interlocking panels.  Synthetic ice is sometimes called artificial ice, but that term is ambiguous, as it is also used to mean the mechanically frozen skating surface created by freezing water with refrigeration equipment.

Alpha-Pyrrolidinopentiothiophenone: α-Pyrrolidinopentiothiophenone (also known as α-PVT) is a synthetic stimulant of the cathinone class that has been sold online as a designer drug.  It is a analogue of α-PVP where the phenyl ring has been replaced by thiophene.

Alpha-Pyrrolidinopentiophenone: α-Pyrrolidinopentiophenone (also known as α-pyrrolidinovalerophenone, α-PVP, O-2387, β-keto-prolintane, Prolintanone, or Desmethyl Pyrovalerone) is a synthetic stimulant of the cathinone class developed in the 1960s that has been sold as a designer drug.  Colloquially it is sometimes called flakka or gravel.  α-PVP is chemically related to pyrovalerone and is the ketone analog of prolintane.

Cochetopa Pass: Cochetopa Pass is a mountain pass in the Rocky Mountains of south-central Colorado.  It lies on the Continental Divide between the city of Gunnison to the northwest and the town of Saguache to the southeast.  It also lies on the boundary between the Gunnison and Rio Grande National Forests.  Its name is taken from the Cochetopa Hills that it lies within, Cochetopa being the Ute Indian word for "pass of the buffalo".  The original pass is traversed by Saguache County Road NN14, a maintained gravel road.  Another crossing, sometimes called North Cochetopa Pass and more often simply North Pass, and is located nearby on State Highway 114, which is paved and reaches a slightly higher elevation.

Supporting paragraphs: Alpha-Pyrrolidinopentiothiophenone Alpha-Pyrrolidinopentiophenone
Answer: α-Pyrrolidinopentiothiophenone