Sand Terminology

Sand Terminology
Technically, sand is merely a size category. Sand is particulate matter that's larger than silt and smaller than gravel. Different specialists set different limits for sand:

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  Engineers call sand anything between 0.074 and 2 millimeter, or between a U.S. standard #200 sieve and a #10 sieve.
  
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  Soil scientists classify grains between 0.05 and 2 mm as sand, or between sieves #270 and #10.
  
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  Sedimentologists put sand between 0.062 mm (1/16 mm) and 2 mm on the Wentworth scale, or 4 to –1 units on the phi scale, or between seives #230 and #10. In some other nations a metric definition is used instead, between 0.1 and 1 mm.
  

In the field, unless you carry a comparator with you to check against a printed grid, sand is anything big enough to feel between the fingers and smaller than a matchhead.
From a geological viewpoint, sand is anything small enough to be carried by the wind but big enough that it doesn't stay in the air, roughly 0.06 to 1.5 millimeters. It indicates a vigorous environment.
Sand Composition and Shape
Most sand is made of quartz or its microcrystalline cousin chalcedony, because that common mineral is resistant to weathering. The farther from its source rock a sand is, the closer it is to pure quartz. But many "dirty" sands contain feldspar grains, tiny bits of rock (lithics), or dark minerals like ilmenite and magnetite.
In a few places, black basalt lava breaks down into black sand, which is almost pure lithics. In even fewer places, green olivine is concentrated to form green sand beaches.
The famous White Sands of New Mexico are made of gypsum, eroded from large deposits in the area. And the white sands of many tropical islands are a calcite sand formed from coral fragments or from tiny skeletons of planktonic sea life.
The look of a sand grain under the magnifier can tell you something about it. Sharp, clear sand grains are freshly broken and have not been carried far from their rock source. Rounded, frosted grains have been scrubbed long and gently, or perhaps recycled from older sandstones.
All of these attributes are the delight of sand collectors around the world. Easy to collect and display (a little glass vial is all you need) and easy to trade with others, sand makes a great hobby.
Qum terminologiyasi
Texnik jihatdan, qum shunchaki o'lchamli toifadir. Qum loydan kattaroq va shag'aldan kichikroq bo'lgan zarracha moddadir. Turli mutaxassislar qum uchun turli chegaralarni o'rnatadilar:

Muhandislar qumni 0,074 dan 2 millimetrgacha yoki AQSh standartidagi №200 elak va №10 elak o'rtasidagi har qanday narsa deb atashadi.

Tuproqshunoslar 0,05 dan 2 mm gacha bo'lgan donlarni qum yoki № 270 va № 10 elaklar orasida tasniflashadi.
Sedimentologlar qumni Wentworth shkalasi bo'yicha 0,062 mm (1/16 mm) va 2 mm yoki phi shkalasi bo'yicha 4 dan -1 birlik yoki № 230 va № 10 seivalar orasiga qo'yishadi. Ba'zi boshqa mamlakatlarda uning o'rniga 0,1 dan 1 mm gacha bo'lgan metrik ta'rif qo'llaniladi.
Dalada, agar siz bosilgan to'rni tekshirish uchun o'zingiz bilan taqqoslagichni olib yurmaguningizcha, qum barmoqlar orasida his qilish uchun etarlicha katta va gugurt kallagidan kichikroq narsadir.

Geologik nuqtai nazardan, qum shamol ko'taradigan darajada kichik, ammo havoda qolmaydigan darajada katta, taxminan 0,06 dan 1,5 millimetrgacha. Bu kuchli muhitni ko'rsatadi.

Qum tarkibi va shakli
Ko'pgina qum kvarts yoki uning mikrokristalli qarindoshi kalsedonidan tayyorlanadi, chunki bu oddiy mineral ob-havoga chidamli. Qum o'z manbasidan qanchalik uzoqda bo'lsa, u sof kvartsga shunchalik yaqinroq bo'ladi. Ammo ko'plab "iflos" qumlarda dala shpati donalari, mayda toshlar (litiklar) yoki ilmenit va magnetit kabi quyuq minerallar mavjud.

Ba'zi joylarda qora bazalt lava qora qumga parchalanadi, bu deyarli toza litikdir. Yana kamroq joylarda yashil olivin yashil qumli plyajlarni hosil qilish uchun to'plangan.

Nyu-Meksikoning mashhur Oq qumlari gipsdan yasalgan bo'lib, bu hududdagi yirik konlardan eroziyalangan. Ko'pgina tropik orollarning oq qumlari esa marjon parchalaridan yoki planktonik dengiz hayotining mayda skeletlaridan hosil bo'lgan kaltsit qumidir.

Lupa ostidagi qum donasining ko'rinishi sizga bu haqda biror narsa aytib berishi mumkin. O'tkir, tiniq qum donalari yangi singan va tosh manbasidan uzoqqa olib ketilmagan. Dumaloq, muzli donalar uzoq va muloyimlik bilan tozalangan yoki ehtimol eski qumtoshlardan qayta ishlangan.

Bu atributlarning barchasi butun dunyodagi qum yig'uvchilarning zavqidir. Yig'ish va namoyish qilish oson (sizga ozgina shisha flakon kerak) va boshqalar bilan savdo qilish oson, qum ajoyib hobbi qiladi.