How to make a crystal from copper sulfate

Chemical gems from copper sulfate

There are many sim­ple and en­ter­tain­ing chem­i­cal ex­per­i­ments you can con­duct with chil­dren. Start to learn about the mag­ic world of crys­tals right now.

At home, you can grow crys­tals from al­most all salts, but it’s best to start mak­ing them with tech­no­log­i­cal­ly sim­ple ma­te­ri­als. These are kitchen salt, sug­ar, bo­rax and cop­per sul­fate. This can be used to make beau­ti­ful, large blue crys­tals. The process of mak­ing them is sim­ple, but very in­ter­est­ing and ed­u­ca­tion­al. Our ar­ti­cle will help you to learn step by step how to make cop­per sul­fate crys­tals at home.

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List of in­gre­di­ents

Here what you'll need to start work on grow­ing the crys­tals at home.

Cop­per sul­fate

You can buy cop­per sul­fate in any gar­den­ing store. It is sold in pack­ets of 100 grams. This cop­per sul­fate is light blue be­cause of its low pu­ri­ty. Crys­tals made from it will be brighter.

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Cop­per sul­fate is also sold in spe­cial lab­o­ra­to­ries that sell reagents. From this cop­per sul­fate, dark blue crys­tals are grown, which look like pre­cious stones.

Con­tain­er for the so­lu­tion

Use a glass ves­sel, as oth­er ma­te­ri­als en­ter into a chem­i­cal re­ac­tion with the so­lu­tion. A jar with a wide neck, with a vol­ume of 0.5 liters, will be ide­al. It is cat­e­gor­i­cal­ly for­bid­den to use it for food af­ter the ex­per­i­ment.

Base for crys­tal­liza­tion

For the base, use a thin woolen thread of a blue or black col­or. The adult crys­tal is semi-trans­par­ent, and the base should not spoil the re­sult. An al­ter­na­tive is a cop­per wire of small di­am­e­ter, pol­ished with sand­pa­per be­fore­hand.


When cop­per sul­fate from a hard­ware store is used for the ex­per­i­ment, boiled wa­ter should be used. If the cop­per sul­fate is of high pu­ri­ty, the so­lu­tion is made with dis­tilled wa­ter.

Pro­tec­tive equip­ment

The sul­fate is tox­ic, and you should not work with it with­out gloves. Young chil­dren should wear med­i­cal masks.

Pen­cil or stick to hold the base

Use it for hang­ing the thread with fu­ture crys­tal.

Trans­par­ent nail pol­ish

To pre­serve crys­tals.

Dis­pos­able plas­tic spoon

At­ten­tion! Only con­duct the ex­per­i­ment un­der adult su­per­vi­sion. At the end of the process, wash your hands un­der run­ning wa­ter. You should wash them thor­ough­ly. You must not taste the crys­tal or pow­der. If cop­per sul­fate gets into chil­dren’s eyes, help them by rins­ing their eyes with a large amount of wa­ter.

How to make a crys­tal: work stages

So­lu­tion of high con­cen­tra­tion

In wa­ter of a tem­per­a­ture of around 80 de­grees, add cop­per sul­fate, one spoon­ful at a time. Con­stant­ly stir the liq­uid, so the pow­der dis­solves com­plete­ly. It’s im­por­tant to main­tain a con­stant wa­ter tem­per­a­ture, for which you can use a wa­ter or sand bath. If the cop­per sul­fate stops dis­solv­ing and be­gins set­tling at the bot­tom, the so­lu­tion is ready. On av­er­age, 200 grams will be used with 300 ml of wa­ter.


Crys­tal seed­ing

Place the con­tain­er with the hot so­lu­tion on a cool­ing sur­face and wait for it to cool down to room tem­per­a­ture. This is so the small crys­tals set­tle. Strain the so­lu­tion through a lay­er of gauze, ex­am­ine it and take the largest crys­tal with a cor­rect form. This will be used as a crys­tal seed­ing to con­tin­ue the ex­per­i­ment.

En­vi­ron­ment for grow­ing the crys­tal

Heat the strained so­lu­tion again in a wa­ter bath, once more bring­ing the con­tent of the cop­per sul­fate to over­sat­u­rat­ed. If the re­sult­ing sed­i­ment does not dis­solve, re­peat the strain­ing. Tie the seed­ing and place it in the jar so the thread is ver­ti­cal, with­out touch­ing the bot­tom or walls of the con­tain­er. You can achieve this with a pen­cil: tie the thread in the mid­dle, and fix the pen­cil on the neck, for ex­am­ple with plas­ticine. Here you’ll find de­tailed in­struc­tions and sci­en­tif­ic de­scrip­tion of this ex­per­i­ment.

Growth of the crys­tal

Cov­er the con­tain­er with a fab­ric hand­ker­chief and leave it for sev­en days in a mo­tion­less state. This is es­sen­tial for the crys­tal to start to form. One week lat­er, you will see that the thread is cov­ered in small crys­tals, one mil­lime­ter and more in size, and the seed­ing has in­creased in size by around 1 cm. The larg­er the crys­tal of cop­per sul­fate be­comes, the faster it will grow. When the re­sult is sat­is­fac­to­ry, dry the crys­tal and cov­er with var­nish. This will stop a white coat­ing from form­ing and pro­vide an ad­di­tion­al shin­ing ef­fect.

In con­duct­ing the ex­per­i­ment, chil­dren will find an an­swer to the ques­tion: “why do crys­tals form”, and will hap­pi­ly make new dis­cov­er­ies.