Read More
Date: 23-3-2017
1154
Date: 27-4-2019
1061
Date: 18-6-2019
815
|
Occurrence of group 2 metals
Beryllium occurs principally as the silicate mineral beryl, Be3Al2[Si6O18] it is also found in many natural minerals, and precious forms include emerald and aquamarine. Magnesium and calcium are the eighth and fifth most abundant elements, respectively, in the Earth’s crust, and Mg, the third most abundant in the sea. The elements Mg, Ca, Sr and Ba are widely distributed in minerals and as dissolved salts in seawater; some important minerals are dolomite (CaCO3.MgCO3), magnesite (MgCO3), olivine ((Mg,Fe)2SiO4), carnallite (KCl.MgCl2.6H2O), CaCO3 (in the forms of chalk, limestone and marble), gypsum (CaSO4.2H2O), celestite (SrSO4), strontianite (SrCO3) and barytes (BaSO4). The natural abundances of Be, Sr and Ba are far less than those of Mg and Ca (Figure 1.1).
|
|
15 نوعا من الأطعمة تساعدك على ترطيب جسمك خلال موجة الحر
|
|
|
|
|
دول عربية تقرر قطع الكهرباء لساعات محددة يوميا بسبب الحرارة
|
|
|
|
|
بالصور: بمناسبة عيد الغدير الاغر.. قراءة خطبة النبي الأكرم (ص وآله) بالمسلمين في يوم (غدير خم)
|
|
|